http://www.peterdoyleconsultancy.com.au/crops.html#tomatosPeter DoylePeter Doyle, is one of Australias foremost hydroponics systems consultants and apassionate advocate for the merits of hydroponics. To Peter, hydroponics offers all thedynamics of certified organic produce grown in soil; and then some. Hydroponics usesexactly the same trace elements found in soil but without the soil; it is intensive farming, thatis fungicide and pesticide free and it is grown without synthetic fertilisers. Additionally it isclimate, weather & terrain independent and the methodology that Peter advocates recyclesthe nutrient solution and uses less water than alternative methods.When Peter began commercially growing herbs and vegetables in the early nineties, he setabout researching and developing techniques, methods and materials that inevitably foundtheir way into the industry through the osmotic relationships he maintains with many leadingsuppliers. In 2002, and in answer to the needs of drought stricken Australian farmers, Peterdeveloped a new hydroponic fodder growing system using a combination of expertise,experience, knowledge and a unique hydroponic feeding method. Designed to consistentlyproduce high protein green feed in adverse conditions, the Commercial Hydroponic FodderSystem (CHFS) utilizes environmentally sound WaterWise methods, and as such requiresmuch less water than field grown crops. The design was granted a patent in 2003.Now that hydroponically grown fodder is proven for commercial purposes the hydroponicsystems Peter designs for plant cultivation are to be found spread across different parts ofthe globe from Morocco to the USA. Consequently many consider him as a leading figure inthe industry worldwide and an Authority on hydroponic system design. More info is availableon the ´Fodder´ link above.The ConsultancyAside from operating a commercially successful hydroponic herb growing business Peteradvises government authorities and educational institutions; and designs customisedHydroponic System solutions and Livestock Fodder Systems for commercial enterprises,farmers, livestock & agricultural organisations.Through his consultancy Peter and his team provide customers with either practical,straightforward information or they design and advise how to set up and run commercialhydroponic systems.The response from PDCs clients indicates that what we do is meeting customersexpectations with consistent results being achieved in all areas of our market. We welcomeand encourage customer communication about new ideas and improvements they havedeveloped as these can only assist our Company and the industry to move forward in thedirection it must surely go.On this page you can find a brief overview of the most common crops grown in commercialhydroponic systems throughout Australia. It is by no means an exhaustive list of these crops,and we have included it only to serve as a reference point for prospective growers. If the cropyou are thinking about growing is not listed, then please contact us, and we will try to fill inthe gaps for you.Tomatoes
One of the most popular crops grown in hydroponicstoday, tomatoes are a good option for hydroponicgrowers due to the demand for the fruit throughoutAustralia (and the world!). It must be noted however,that growing tomatoes is not for everyone due therelatively high labour input required between crops,and the need to pick quite large numbers on a regularbasis. Care should therefore be taken beforeestablishing a growing system based around this crop,and we would always recommend spending sometime on an existing farm to get a feel for the amount ofinput required before committing to a commercialhydroponic tomato system.There are currently a variety of different methods being used in the hydroponic production oftomatoes of which the most common are NFT and Drip Irrigation. NFT will provide thegreatest yield at the least cost, but this has not been taken on by all growers yet for variety ofdifferent reasons (mostly related to the saying “If it’s not broke, don’t fix it”). But this isstarting to change, and more and more growers are changing over to NFT.A major consideration when thinking about setting up a hydroponic tomato farm is the initialcost involved. Because tomatoes are a vine crop and require support from above, you willneed a hothouse that can support their weight. There are of course plenty of companies outthere that can sell you one of these structures, but it is a major expense, and may place astrain on your budget. However, if you have a good market for tomatoes, this initial cost canbe quickly recovered.Tomatoes also require pollination to set their fruit, as well as a environmental managementsystem to keep require as the plants like them for optimum growth. So be prepared for quitea sharp initial learning curve if you make the final decision to move into this field ofcommercial hydroponic farming, and always remember, you get out what you put in.top of the pageCapsicumAlthough capsicum and tomatoes are similar in their method of production, there are somesignificant differences. For a start, nearly all capsicum are currently grown in medium basedsystems as opposed to NFT. This system utilizes the “batch feeding” technique, which allowsfor climatic conditions to dictate the feeding frequency and volume, i.e when it is hot, youfeed more at more regular intervals than when it is cold, to allow for increased uptake by theplants. It is by all accounts a tried and tested method of growing capsicum with many yearsof proven results, and should be carefully considered by all growers looking at starting acapsicum farm. However, we are in some ways a “pro NFT” hydroponic consultancy, and would recommend that all new growers also have a good look at the nutrient film technique method before committing to any commercial growing system. We know that in a well designed NFT channel, results equal to drip feeding media based systems are easily obtainable, with a marked decrease in labor costs. Setup costs are much the same, with the only difference being how long the plant is left on the system. In a media based system plants will tend be grown as perennials and will produce many sets of fruits throughout the year, but
will require a fair amount of attention to ward of pests and long term nutrient imbalances. InNFT plants tend to be grown as annuals, and therefore only produce fruit for a limited periodof time, but do not tend to suffer from many of the problems associated with the perennialsdue to the ability to remove any under productive or diseased plants after a much shorterperiod of time. With this type of crop, if the worst happens it is only a minor setback, and canusually be incorporated into a slightly revised planting schedule.A couple of other points to note with capsicum are that as with other vine crops, capsicumrequire a hothouse or structure that can support the weight of the plant from above, and thatyou must always have a very good look at the local market to determine whether or not yourbusiness has the potential to be a success in its early stages before going ahead with yourventure. With capsicum, you are very dependent on your market to make your businesssuccessful, with a relatively small margin for errortop of the pageCucumbersCucumbers are in many respects similar to tomatoesand capsicum in their method of production, with themost notable difference being their vulnerability to coldtemperatures. The air temperature in the hothousecannot be allowed to dip below 70 deg F withoutstress occurring to the plant, and the nutrient solutionwill normally have to heated as well. This mayincrease energy costs significantly in colder regions,but could also be an advantage to prospectivegrowers in hotter climates.Again, as with tomatoes and capsicum, cucumberscan be grown as either a short term crop, or as a long term crop. Short term NFT crops offera considerable saving on labour costs, and as such are being used more and more as theproduction method of choice for cucumbers. Other methods of cucumber include dripirrigation culture into mediums such as perlite and rockwool, and the Deep Flow Technique.Hothouse structures must be capable of supporting vine crops weight, which coupled withthe need to keep cucumbers over a certain temperature and the potential energy costsassociated with this, mean that careful investigation of your market is essential beforeembarking on a cucumber growing venture.top of the pageHerbsThe markets in Australia generally require two types of product, the first of which is the “freshcut” product. This type of product can be grown in either NFT or medium based systems, asthe leaves of the herbs are cut away from the roots for processing into sealed bags orcontainers. The second type of product commonly seen on the Australian market today is “living plant” herbs. Here the plant is grown in NFT and harvested whole with the root system intact. The herbs are then placed into a plastic bag with a small amount of water or nutrient, and sold as a single unit. This method provides the retailer with a significant increase in shelf life thus reducing the wastage experienced with the fresh cut
herbs.Commonly grown herbs in NFT are basil and coriander, and they seem to be particularlysuited to this method of production. Herbs such as thyme, marjoram and sage are oftengrown in a medium based system, but can be grown just as well in NFT.Most herbs can be grown in a variety of conditions and due to their relatively short lifespan,can be grown with a good degree of success in most climates. They also grow very well onthe same system as lettuce, allowing a wider range of products to be marketed.Growing herbs in NFT is one of the least physically demanding types of commercialhydroponic production, and within reason, can usually be operated by a husband and wifeteam.top of the pageLettuceThere are many different types of lettuce grown today which include all the different types oflettuce normally sold in supermarkets throughout Australia and NZ. The method of growing isnearly always NFT, which as with herbs, allows for the finished plants to be sold as either“fresh cut” or “living plant”.While the market for lettuce in the bigger cities may bedifficult to access, there are opportunities in regionalareas for smaller systems of say 1,000 to 1,500square meters to meet the demand for ‘local’ freshproduce. As with all commercial systems we can notover emphasize the importance of establishing apotential market first. Whether you develop a simple or‘high tech’ commercial system, the exercise ispointless if you have nowhere to sell your produce.Romain or cos lettuce are currently very popularamongst commercial hydroponic growers. Varietiesinclude; Red Romaine (tolerant to both heat and cold), Paris White, Parris Island, Cos Verdi,Toledo, Marvel, Diamond Gem, and Little Gem to name a few.Growing time for lettuce can be anywhere between 60 and 80 days, and these plants canoften be grown outdoors with relative ease in hotter climates. This of course can save quite alot money on the initial outlay for a commercial farm, and is one of the reasons that lettuce isso popular with many commercial hydroponic growers. Another reason is the ability to growherbs such as basil and coriander alongside lettuce to increase the range of produceprovided by the grower.top of the pageOrnamentals There are currently many different types of ornamental flowers under hydroponic production today, with some of the most common being gerberas, carnations, lisianthus, roses and chrysanthemums. The main difference between ornamental crops and food crops (apart from the obvious), is the level of environmental control needed to achieve optimum
growth. The parameters for ornamental production are very rigid to say the least, and setupcosts can be daunting.Another problem being faced by hydroponic ornamental growers is competition from abroadin addition to the down turn in the tourism and hospitality industry. Careful consideration mustbe given prior to venturing into the commercial flower industry, where a confirmed market isessential. Also the threat of cheap ornamental imports from across the globe can mean thata once solid and reliable outlet for your produce can suddenly be faced with the option ofreducing there costs considerably, and few retail sellers will be able to say no this sort ofincentive. After all, if they don’t take the flowers at a cheaper price then the shop next doorprobably will, and they will lose business to them. With this in mind careful market research isan absolute must for this type of start up, and the worst case scenario must be your startingpoint.Given the complexities in growing commercial ornamentals, a good alternative could be to‘learn the ropes’ on a more forgiving hydroponic system such as herbs or lettuce, as therealways tend to be a good market in most regions. As your knowledge and capability increaseit may be possible to approach local ornamental retailers with some sample produce to see ifthey are interested. In this way you have something to show the retailer when you do yourmarket research, in addition to having a good idea of your production costs (and thereforeyour break even price), and by then you should know whether or not ornamental growing isfor you.We don’t mean to sound negative on this subject, but it is no secret that at the momentcurrent market conditions in Australia for ornamental plants are a bit volatile, and new startups may experience significant difficulties in gaining a foothold into the market place. Thatsaid, if you have a good market, we will of course happily consult on ornamental flowerproduction for you. Other crops include:-top of the pageOther crops include :-VINE CROPS BRASSICASTomatoes (Lycopersicon lycopersicum) Broccoli (Brassica oleracea var. italica)Capsicum (Capsicum annum) Cauliflower (Brassica oleracea var.Cucumber (Cucumis sativa) botrytis) Cabbage (Brassica oleracea var. capitata)HERBS Rocket (Brassica rapa . var. chinensis)Dill (Anethum graveolens) Kale (Brassica oleracea var. acephala)Parsley (Petroselinum crispum)Chives (Allium schoenoprasum) VEGETABLESMint (Mentha app.) Aubergine (Solanum melongena var.Tarragon (Artemisia dranunculus) esculentum)Marjoram (Maiorana hortensis) Carrots (Daucus carota)Fennel (Foeniculum vulgare) Spinach (Spinacia oleracea)Sorrel (Rumex acetosa) Asparagus (Asparagus officinalis)Chicory (Cichorium intybus) Okra (Hibiscus esculentus)LETTUCE ROOT VEGETABLESCrisphead (Lactuca sativa var. capitata) Potato (Solanum tuberosums)Butterhead (Lactuca sativa var. capitatis) Radish (Raphanus sativus)Vietnamese (Lactuca sativa var. crispa) Onion (Allium cepa)Romaine/Cos (Lactuca sativa var. Carrot (Daucus carota)longifolia) Spring Onion (Allium fistulosum)ASIAN VEGGIES SPICES
Amaranth (Amaranthus tricolour) Root Ginger (Zingiber Officionale)Buffalo Spinach (Enydra fluctuans) Turmeric (Cucurma domestica)Chinese Flowering Cabbage (Brassica Curry Leaves (Murraya koenigii)rapa var. parachinensis)Chinese Celery (Apium graveolens var. FRUITdulce) Watermelon (Citrullus lanatus)Hot Mint (Poligonum minus)Lemon Grass (Cymbopogon citratus)Lizard’s Tail (Hottuynia cordata)Mustard Green (Brassica juncea)Pak Choi (Brassica rapa var. chinensis)Pennywort (Centella asiatica)Perilla (Perilla frutescens)Thai Basil (Ocimum basilicum)Spearmint (Mentha viridis)Turmeric (Cucurma domestica)Water Convolvulus (Ipomea aquatica)Water Parsley (Oenanthe javanica)Watercress (Rorippa nasturtium-acquaticum) -----o0o-----Our experience and expertise in the Hydroponicsmarket is unrivalled in Europe…”Let’s talk about Commercial Hydroponics…With many years of experience HydroGarden is the UK leader in hydroponics. We haveassisted many growers develop their businesses with our access to experts and consultantsin a wide range of topics including plant biochemistry, analytical chemistry, commercialgrowers with crop specific knowledge, commercial installation experience and much more.Several directors within HydroGarden have owned and operated their own commercialhydroponic operations.Hydroponics is also now recognised as an important research tool. It has particularadvantages where various controls are needed such as the pharmaceutical industry andother areas of research where a clean root system is required for instance.In Australia hydroponics production has risen from 155 hectares in 1990 to 500 hectares in1996. This growth continues.In progressive, forward thinking countries throughout the world the commercial hydroponicsindustry has increased 4-5 fold during the last 10 years. It is currently estimated that the areaunder hydroponic cultivation is between 20,000 and 25,000 hectares with a farm gate valueof US$6-8 billion.HydroGarden believes that the future lies in locally grown and sold produce, limiting the ‘roadmiles’ applied to today’s food supplies. Whilst export opportunities will occur, the maindevelopment will be that smaller niche, locally based growers will sell to supermarkets,farmers markets and wholesale operations as well as the consumer direct. This method ofgrowing our food is a more sustainable model than those currently practised. Today’sconsumer has become increasingly aware of health and environmental issues, even waterconsumption and availability…these are all drivers for the further development of hydroponicgrowing techniques.As a company HydroGarden can assist you to identify the most suitable system for your
crop, location, skills and needs. We understand that different plants require different systemsin different locations and as such can offer those systems how and when you need them…Why use Hydroponics?There are 5 forces threatening long term crop and food production in open field situations:1 Increasing ultraviolet radiation2 Decreasing fresh water supplies and water quality3 Increasing top soil erosion and soil degradation4 Increasing resistance of insect pests and plant diseases to traditional chemical controls5 A convergence of natural cycles leading to extreme weather conditionsFurther, open field production is hindered because the grower has no control over thegrowing environment. The result is that the grower cannot predict yields and is unable tobudget effectively. The field grower cannot always ensure adequate aeration of the rootzoneduring periods of extended rainfall.The results might be any of the following:Anaerobic conditions will benefit the proliferation of fungus (Phytophthora sp.) andnematodes that will attack the roots and eventually kill the plant.Roots need oxygen to respire and therefore are not productive when the soil is saturated forlong periods.Beneficial soil borne micro-organisms are eliminated, therefore exposing the roots to fungaland bacterial attack.Rain and excessive irrigation on the soil will leach essential nutrients from the root profile.Nitrates can be washed through the soil profile and pollute streams, reservoirs and the sea.Hydroponic nutrient solutions can be tailored to the plant requirements whereas in the fieldthere is a tendency to over or under-fertilise. Nutrients in the soil are often fixed as insolublecompounds that are not available to plants and therefore a loss to the grower.SOIL GROWN HYDROPONICALLY GROWNSmall plant - big root Big plant - small rootLooking at the benefitsIrrigation water in field grown operations cannot be effectively recycled. Hydroponics canreduce irrigation water usage by 70% to 90% by recycling the run-off water. As water
becomes scarce and more important as a resource, the use of hydroponics and other watersaving technologies will increase.Fungal disease can be significantly reduced through controlled humidity. Hydroponicsystems will reduce the amount of exposed moisture in the growing environment.Hydroponics will effectively prevent wetting the leaf surfaces which, in normal agriculture,provides the fungal spores with the perfect medium to proliferate.All labour inputs associated with soil management, such as digging and weeding aresubstantially reduced with hydroponics.The use of Integrated Pest Management (IPM) in protected environments is ideally suited tohydroponic growing techniques, especially when carried out in a protected environment suchas a glasshouse or plastic/polythene tunnels. The use of IPM can virtually eliminate the needto use toxic and expensive chemical insecticides.Taking all the above into account, it is easy to see why protected cropping in general andhydroponics especially is becoming increasingly important.A hydroponically grown greenhouse plant:Can be protected from increasing and damaging UV radiationOffers the possibility of safe biological control of insect pests and diseasesUses water that is reclaimed and reusedAllows nutrients to be reclaimed, re-balanced and re-usedCan be protected from unpredictable weather patternsHas a good root system that is at reduced risk from contaminants and diseasesMakes very efficient use of labour, which is increasingly expensive in western economiesCan be grown to take full advantage of their genetic potential and produce outstanding cropsby using optimum nutrient formulationsCan be producing at times when market prices are highestCombine these factors with increasing public concern over food safety, pesticide residuesand fungicide use; it is easy to see that the future of crop production favours hydroponic andgreenhouse production. Especially when premium prices can be obtained and the demand issustainable.Global diversity…Lettuce, strawberries and cut flowers are well known commercial hydroponic crops inAustralia, and have been for the past decade and more. Tomatoes, pepper, cucumbers andcut flowers form the bulk of Dutch hydroponic crops. A number of UK growers havesuccessful cucumber and tomato operations and many herb growers are moving into thisform of cultivation. Nowadays plants for essential oils, rare herbs, medicinal plants andChinese vegetables such as pak choi are more recent crops of great interest. There is adeveloping interest in growing plants for pharmaceutical and nutraceutical use. It is possibleto grow practically any commercial crops hydroponically.Commercial growers have been producing superbly flavoured hydroponic tomatoes for manyyears. Speciality crops and even fruit trees can all be grown hydroponically.We have recently learnt of a commercial hydroponic potato business in the Southern
Hemisphere !We are seeing an increasing interest in the production of cut herbs and salad crops, drivenby the demand for convenience foods that are also seen as ‘healthy’.The production of cut flowers is itself a huge market, the introduction of new more exoticplant types lends itself to hydroponic production as a means of growing the best quality fromthe outset and therefore making it more difficult for cheaper lower quality crops to compete.We expect, in time, to see an increase in demand for edible flowers, especially for use inrestaurants and hotel complexes.Even fruit trees can be grown this way. In fact there are very few plants that cannot be grownhydroponically, the choice for a commercial operation is a pure economic one.We produce a number of separate data sheets relating to various crop types andopportunities, this information includes some basic plant growing information as well asrecommended or typical system types suitable for the crop. Whilst it is not exhaustive it willgive the reader an idea of the potential for hydroponic crop production.Commercial systems…All commercial systems are active, in that some form of pump or feeding device is used todeliver fresh nutrient solution to the plants in an ongoing basis. These systems are moreproductive and are therefore the only type suitable for commercial production.Of the active systems available they break down into either re-circulating or run to waste; runto waste systems are becoming less popular as environmental concerns and legislationrestricts, or even prohibits, nutrient run off. However, if the run off can be managed to obtaina zero figure, these systems still have their place. As a company we encourage the use of re-circulating systems to maximise resource utilisation, but this is not always possible in certaincircumstances. Re-circulating systems typically use one tenth of the water, a fraction of theminerals and takes up from one third to one tenth the space consumed in traditionalagriculture.There are a number of differing active systems available, but again these can beeasily categorised into:Nutrient Film Technique (NFT)Ebb & Flow (also referred to as Flood & Drain)Drip Fed Media Based CultureAeroponicsRaft Type SystemsNutrient Film Technique (NFT)Nutrient Film Technique (NFT) is both simple to understand, operate and maintain. Plants are grown in equally spaced holes in plasticgullys or formed plastic sheeting. A liquid nutrient solution of minerals and highly oxygenated water is pumped into the higher end of thegully, gravity draws the nutrient past the plant roots and then back to the nutrient tank, where the process is repeated.As the nutrient solution flows past the plants the roots are bathed in a thin nutrient rich film of solution that is ideally balanced in terms ofnutrition, oxygen, pH and strength. As this is an enclosed re-circulating active system it ensures maximum production combined withresource conservation.The absence of growing media in NFT systems reduces costs but ensures the need to use high quality pumps and calls for a reliablepower supply to those pumps. The plants will quickly wither and die if the system is left ‘dry’ during the heat of the day.Drip Fed Media Based CultureOften called ‘slab culture’, this is most popular form of commercial hydroponics in countriessuch as Holland. The plants are grown in a medium, most often Rockwool but more recentlyin CoCo Coir. However, sawdust and sand have been used in some instances!
Slab Culture tends to be used for longer-term crops such as tomatoes, cucumbers andpeppers where a larger root system develops. The advantage of slab culture is that onlyintermittent feeding of the plants is required. Also, the media itself tends to hold a largeamount of nutrients that are then available to the plants as needed. Often run off is limited toa small percentage to ensure adequate feeding, but excessive run off is both expensive andenvironmentally undesirable. As in ‘Ebb & Flow’, the media can act as a buffer in case ofpump or electricity failure.Ebb & FlowEbb & Flow (or Flood & Drain) is a system where a tray or bed of plants arealternatively flooded and then drained with the required nutrient solution. The flooding of themedia or plants acts to purge the media of stale oxygen depleted air and then draws in freshoxygen rich air to the root-zone when the system drains back into the nutrient tank.This system is more suitable for longer-term crops such as trees & cut flowers where largerroot masses are likely. Ebb & Flow systems always use some kind of media that can act as abuffer in case of pumps or electricity failure. Also, because the system is less active than anNFT system the management of the nutrient solution is often less onerous thanthat of NFT.AeroponicsAeroponics is a system where often no media is present at all and the roots of the plants aremisted with the nutrient solution in a chamber or other suitable space. The mist has to be of acertain size (5 micron max) to maximise growth and the delivery of the mist is a problem in itsown right. Blockages can occur and high-pressure pumps are often needed, this makesAeroponics less suitable for commercial production. However, we are aware of Aeroponicsystems being used for research and in some‘niche’ applications.The lack of any media in Aeroponics and the subsequent lack of buffering canbe problematic, but Aeroponic is a fantastic system when clean, fresh roots are needed!Raft Type SystemsRaft Type Systems are those where the plant being cultivated is ‘floated’ on top of thenutrient tank. The roots dangle in the nutrient and take up feed as needed. A large amount ofwater is generally needed for such systems and the need to oxygenate the solution isparamount. It would be easy to ‘drown’ the plants if the oxygenation system failed. Raftsystems are generally regarded as a bit outdated, but do have their place in certaincircumstances.They are often cheap to construct and can be run without the use of nutrient pumps as longas oxygen is supplied to the system in suitable quantities.Some concerns exist over the use of re-circulating systems and the potential danger ofspreading disease throughout the system if it manifests itself. However, in our experiencethis danger can be greatly reduced and even eliminated through the use of nutrientsterilisation, strict cleanliness regimes or beneficial bacteria being used.All of the system types discussed usually utilise automatic dosing controllers to constantlymonitor and maintain the optimum nutrient strength and pH balance.As a company, we can advise on all system types and the suitability of that system to anindividual case.Whatever system is most suitable for your operation, we can supply it.For any new grower we are happy to provide a small trial system at a special price.The cost of this system would be credited to the grower should a full size system bepurchased as a result of the trial.
Getting started…It is most important when considering the possibility of growing hydroponically, whether on asmall or large scale, that you seek advice from a number of sources. Talk to potentialcustomers and fully research the business. We will assist where ever possible. Carry outresearch before you start and plan to start small! Each market, each crop and every growingsituation is different. It will be necessary to gain an overall understanding of the business andcrop before any significant system expansion takes place.Don’t rely on a single source when obtaining information on crop yields for a specific crop,check local as well as national and government sources.We recommend the grower starts off with a small trial system, we can advise and assist withthese too. A trial system enables the grower to get the hang of the basics of hydroponics. It iseasy, but you have to learn how to use it properly, how to get the correct balance of nutrientsfor the correct flavour or colour and growth of the plant and how to recognise problems asthey arise.Buy a good book. We sell several that are crop specific, and do some reading.If possible visit an existing commercial grower - we may be able to help in providing contacts.Ensure you perform adequate market research. Marketing is customer not product focussed.If possible innovate to continuously improve product benefits. Try to add value as this willattract new customers for your produce and ensure you keep existing ones.There is much more to running a successful commercial operation than just growing highquality produce. HydroGarden can advise on various ways to market your produce and howto add value and with more general marketing advice.Growing hydroponically will give you the ability to time harvests to match restrictedavailability for certain crops, this aids in obtaining premium prices for the crop.If necessary, we have the expertise in other business topics such as finance, which may alsoassist.By reading this brochure and by using the services offered, you will save time, effort andmoney.All under one roof…Please refer to our Commercial Price List for the complete range of our products.Not only can we provide the system, lighting and nutritional requirements for your system, wealso stock a large range of other essential items such as:growing mediapropagating productslow and high pressure pipe fittingsnutrient pumpsgrowth promoting and flowering additivespH testing, adjustment and calibration productsnutrient testing and calibration productsnutrient sterilisation productsaeration productsmonitoring and dosing equipmentfilters and filtration productsplant support accessories to aid optimum growthbooksand more....It is important to remember that all components used in a hydroponic system must be non-
toxic and must not react when exposed to the nutrient solution. This generally means plasticor stainless steel materials.Trial SystemsAs a company we would always recommend that a new grower purchase a trial system in thefirst instance. This will get you used to the techniques behind hydroponic cultivation and getused to the control of the nutrient strength and pH.HydroGarden Trial System Offer!We are always happy to deduct the cost of this initial trial system from the cost of any fullsize system should you choose to purchase one. It all helps.A helping handAt Hydrogarden, we realise that a relationship starts, not ends, with a purchase of a system.We are able to assist from the business or system planning stage, all the way through to on-going grower support. We may even be able to help you buy or sell your business.HydroGarden can assist you prior to starting growing with:Water AnalysisCrop Specific NutrientsLocation Specific NutrientsLocation and Natural Environmental ConsiderationsCrop Considerations as well as Yield Forecasts and PredictionsSystem Layout, Specification and ConsiderationsEnvironmental Control and Protective Structural ConsiderationsProduction Factors and Operating CostsManagement and Grower ConsiderationsAdditional Resources that may be requiredSupplementary Lighting Layout (if necessary)Equipment SupplyBusiness PlanningMarketing AdviceOnce the system is operational, we can advise, or obtain advice on:Crop Specific Problems or IssuesPlant Tissue AnalysisNutrient Analysis/Monitoring/Tissue Analysis and Nutrient Adjustment and ReplenishmentEquipment Supply or UpgradesLatest Technical Information and InnovationsEquipment SupplyMarketing AdviceEmbracing the new…Energy Conservation and Renewable EnergyWe firmly support all initiatives to reduce unnecessary energy consumption in the projects weare involved with. Where possible we will assist in lowering a grower’s dependence uponfossil fuels.The use of energy efficient glass or plastic structures, energy curtains, heat sinks, correctdesign, location and layout, the correct use of ventilation and other initiatives can all assist in
making the project successful and sustainable.The use of bio-fuels and other alternative sources of power such as micro-turbines can allassist in making the commercial hydroponics industry a viable, long term one.New Markets and Evolving OpportunitiesMedicinal – Nutraceuticals – Cosmeceuticals – Pharmaceuticals – Essential Oils – HerbalMedicines - Healthy Food – Safe Food – Farmers Markets – Localised Supply - Hydro-0rganics - Utilisation of brown field sites - Urban HorticultureRecent reports give reliable predictions that natural based products will penetrate thesynthetic pharmaceutical markets by up to 30% over the next 3 years (from 2003). Where willthese plant-based products be sourced? Nutraceuticals (foods that are beneficial to ourhealth) are also expected to maintain the growth seen over the past decade. A number ofthese foods require plant-derived materials that are often found in a plant’s root zone. Theuse of hydroponic growing methods alone can ensure the clean, controlled product that isrequired. Pharmaceutical companies also need raw materials that are pesticide free, of highquality and have been grown in a controlled method…sound familiar? They have to be grownin controlled, clean environments such as hydroponics can provide. It is unlikely that thisgrowth in demand will be met by ravaging the already delicate eco-systems represented byrainforests and similar natural resources.In the USA it is common for high value foods to be grown hydro-organically, that is usingorganic nutrients in a hydroponic system.The demand for more natural based products is unlikely to diminish in the foreseeable future.Combine these factors with the increasing interest in pesticide free, healthy, vitamin richfoods and you can see why we are so excited about the future prospects of our industry…In conclusion…Over the past 9 years, HydroGarden has been actively involved in the global Hydroponicsindustry and has gained a reputation for the supply of quality products at affordable prices.Our experience and expertise in the Hydroponics market is unrivalled in Europe and weknow that commercial hydroponic systems are serious business. We have contacts withhydroponic companies and commercial growers worldwide.So if we do not know the answer we can find someone who does!As well as designing, supplying and maintaining systems, HydroGarden staff and directorshave hands on experience of growing. This personal experience is something that few, if anyother, firms can claim. We know what it is like when the insects attack or the varieties arewrong. We have also felt the joy of growing the best quality crops in the shortest possibletime!If you are considering entering into hydroponics on a commercial basis, we invite you to talkto us. Not only will you find our company friendly and efficient, our range of quality productsand backup is the best available anywhere.HydroGarden will talk with you about the system you need, the returns you will require andthe obstacles you may encounter.So, if you are after the right advice, equipment and system design, call us today on
+44 (0)24 7660 8080 +44 (0)24 7660 8080 FREE or fax us on +44 (0)24 7665 1060You can also email us or visit our web firstname.lastname@example.orgWikipedia DefinitionHydroponics is a subset of hydroculture and is a method of growing plants using mineralnutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots inthe mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool,expanded clay or coconut husk.Researchers discovered in the 18th century that plants absorb essential mineral nutrients asinorganic ions in water. In natural conditions, soil acts as a mineral nutrient reservoir but thesoil itself is not essential to plant growth. When the mineral nutrients in the soil dissolve inwater, plant roots are able to absorb them. When the required mineral nutrients are introducedinto a plants water supply artificially, soil is no longer required for the plant to thrive. Almostany terrestrial plant will grow with hydroponics. Hydroponics is also a standard technique inbiology research and teaching.
Contents[hide] • 1 History • 2 Origin o 2.1 Soilless culture • 3 Advantages and disadvantages o 3.1 Advantages o 3.2 Disadvantages • 4 Techniques o 4.1 Static solution culture o 4.2 Continuous-flow solution culture o 4.3 Aeroponics o 4.4 Passive sub-irrigation o 4.5 Ebb and flow or flood and drain sub-irrigation o 4.6 Run to waste o 4.7 Deep water culture o 4.8 Bubbleponics o 4.9 Fogponics o 4.10 Rotary • 5 Substrates o 5.1 Expanded clay aggregate o 5.2 Growstones o 5.3 Coir o 5.4 Rice Hulls o 5.5 Perlite o 5.6 Pumice o 5.7 Vermiculite o 5.8 Sand o 5.9 Gravel o 5.10 Wood fibre o 5.11 Sheep wool o 5.12 Rock wool o 5.13 Brick shards
 HistoryFurther information: Historical hydrocultureThe earliest published work on growing terrestrial plants without soil was the 1627 bookSylva Sylvarum by Francis Bacon, printed a year after his death. Water culture became apopular research technique after that. In 1699, John Woodward published his water cultureexperiments with spearmint. He found that plants in less-pure water sources grew better thanplants in distilled water. By 1842, a list of nine elements believed to be essential to plantgrowth had been compiled, and the discoveries of the German botanists Julius von Sachs andWilhelm Knop, in the years 1859-65, resulted in a development of the technique of soillesscultivation. Growth of terrestrial plants without soil in mineral nutrient solutions was calledsolution culture. It quickly became a standard research and teaching technique and is stillwidely used today. Solution culture is now considered a type of hydroponics where there is noinert medium.In 1929, William Frederick Gericke of the University of California at Berkeley began publiclypromoting that solution culture be used for agricultural crop production. He first termed itaquaculture but later found that aquaculture was already applied to culture of aquaticorganisms. Gericke created a sensation by growing tomato vines twenty-five feet high in hisback yard in mineral nutrient solutions rather than soil. By analogy with the ancient Greekterm for agriculture, geoponics, the science of cultivating the earth, Gericke coined the termhydroponics in 1937 (although he asserts that the term was suggested by W. A. Setchell, ofthe University of California) for the culture of plants in water (from the Greek hydro-,"water", and ponos, "labour").Reports of Gerickes work and his claims that hydroponics would revolutionize plantagriculture prompted a huge number of requests for further information. Gericke refused toreveal his secrets claiming he had done the work at home on his own time. This refusaleventually resulted in his leaving the University of California. In 1940, he wrote the book,Complete Guide to Soilless Gardening.Two other plant nutritionists at the University of California were asked to research Gerickesclaims. Dennis R. Hoagland and Daniel I. Arnon wrote a classic 1938 agricultural bulletin,The Water Culture Method for Growing Plants Without Soil, debunking the exaggeratedclaims made about hydroponics. Hoagland and Arnon found that hydroponic crop yields wereno better than crop yields with good-quality soils. Crop yields were ultimately limited byfactors other than mineral nutrients, especially light. This research, however, overlooked thefact that hydroponics has other advantages including the fact that the roots of the plant haveconstant access to oxygen and that the plants have access to as much or as little water as theyneed. This is important as one of the most common errors when growing is over- and under-watering; and hydroponics prevents this from occurring as large amounts of water can bemade available to the plant and any water not used, drained away, recirculated, or activelyaerated, eliminating anoxic conditions, which drown root systems in soil. In soil, a growerneeds to be very experienced to know exactly how much water to feed the plant. Too muchand the plant will not be able to access oxygen; too little and the plant will lose the ability totransport nutrients, which are typically moved into the roots while in solution. These tworesearchers developed several formulas for mineral nutrient solutions, known as Hoaglandsolution. Modified Hoagland solutions are still used today.One of the early successes of hydroponics occurred on Wake Island, a rocky atoll in thePacific Ocean used as a refuelling stop for Pan American Airlines. Hydroponics was usedthere in the 1930s to grow vegetables for the passengers. Hydroponics was a necessity onWake Island because there was no soil, and it was prohibitively expensive to airlift in freshvegetables.
In the 1960s, Allen Cooper of England developed the Nutrient film technique. The LandPavilion at Walt Disney Worlds EPCOT Center opened in 1982 and prominently features avariety of hydroponic techniques. In recent decades, NASA has done extensive hydroponicresearch for their Controlled Ecological Life Support System or CELSS. Hydroponicsintended to take place on Mars are using LED lighting to grow in different color spectrumwith much less heat. Origin Soilless cultureGericke originally defined hydroponics as crop growth in mineral nutrient solutions.Hydroponics is a subset of soilless culture. Many types of soilless culture do not use themineral nutrient solutions required for hydroponics.Plants that are not traditionally grown in a climate would be possible to grow using acontrolled environment system like hydroponics. NASA has also looked to utilizehydroponics in the space program. Ray Wheeler, plant physiologist at Kennedy SpaceCenter’s Space Life Science Lab, believes that hydroponics will create advances within spacetravel. He terms this as a bioregenerative life support system. Advantages and disadvantages This article contains a pro and con list. Please help improve it by integrating both sides into a more neutral presentation. (November 2012) AdvantagesSome of the reasons why hydroponics is being adapted around the world for food productionare the following: • No soil is needed for hydroponics • The water stays in the system and can be reused - thus, lower water costs • It is possible to control the nutrition levels in their entirety - thus, lower nutrition costs • No nutrition pollution is released into the environment because of the controlled system • Stable and high yields • Pests and diseases are easier to get rid of than in soil because of the containers mobility • It is easier to harvest • No pesticide damage • Plants grow healthier • It is better for consumptionToday, hydroponics is an established branch of agronomy. Progress has been rapid, andresults obtained in various countries have proved it to be thoroughly practical and to havevery definite advantages over conventional methods of horticulture.
There are two chief merits of the soil-less cultivation of plants. First, hydroponics maypotentially produce much higher crop yields. Also, hydroponics can be used in places wherein-ground agriculture or gardening are not possible. DisadvantagesWithout soil as a buffer, any failure to the hydroponic system leads to rapid plant death. Otherdisadvantages include pathogen attacks such as damp-off due to Verticillium wilt caused bythe high moisture levels associated with hydroponics and over watering of soil based plants.Also, many hydroponic plants require different fertilizers and containment systems.  TechniquesThe two main types of hydroponics are solution culture and medium culture. Solution culturedoes not use a solid medium for the roots, just the nutrient solution. The three main types ofsolution cultures are static solution culture, continuous-flow solution culture and aeroponics.The medium culture method has a solid medium for the roots and is named for the type ofmedium, e.g., sand culture, gravel culture, or rockwool culture.There are two main variations for each medium, sub-irrigation and top irrigation[specify]. For alltechniques, most hydroponic reservoirs are now built of plastic, but other materials have beenused including concrete, glass, metal, vegetable solids, and wood. The containers shouldexclude light to prevent algae growth in the nutrient solution. Static solution cultureIn static solution culture, plants are grown in containers of nutrient solution, such as glassMason jars (typically, in-home applications), plastic buckets, tubs, or tanks. The solution isusually gently aerated but may be un-aerated. If un-aerated, the solution level is kept lowenough that enough roots are above the solution so they get adequate oxygen. A hole is cut inthe lid of the reservoir for each plant. There can be one to many plants per reservoir.Reservoir size can be increased as plant size increases. A home made system can beconstructed from plastic food containers or glass canning jars with aeration provided by anaquarium pump, aquarium airline tubing and aquarium valves. Clear containers are coveredwith aluminium foil, butcher paper, black plastic, or other material to exclude light, thushelping to eliminate the formation of algae. The nutrient solution is changed either on aschedule, such as once per week, or when the concentration drops below a certain level asdetermined with an electrical conductivity meter. Whenever the solution is depleted below acertain level, either water or fresh nutrient solution is added, A Mariottes bottle, or a floatvalve, can be used to automatically maintain the solution level. In raft solution culture, plantsare placed in a sheet of buoyant plastic that is floated on the surface of the nutrient solution.That way, the solution level never drops below the roots. Continuous-flow solution cultureIn continuous-flow solution culture, the nutrient solution constantly flows past the roots. It ismuch easier to automate than the static solution culture because sampling and adjustments tothe temperature and nutrient concentrations can be made in a large storage tank that haspotential to serve thousands of plants. A popular variation is the nutrient film technique orNFT, whereby a very shallow stream of water containing all the dissolved nutrients requiredfor plant growth is recirculated past the bare roots of plants in a watertight thick root mat,which develops in the bottom of the channel, has an upper surface that, although moist, is inthe air. Subsequent to this, an abundant supply of oxygen is provided to the roots of theplants. A properly designed NFT system is based on using the right channel slope, the right
flow rate, and the right channel length. The main advantage of the NFT system over otherforms of hydroponics is that the plant roots are exposed to adequate supplies of water,oxygen, and nutrients. In all other forms of production, there is a conflict between the supplyof these requirements, since excessive or deficient amounts of one results in an imbalance ofone or both of the others. NFT, because of its design, provides a system where all threerequirements for healthy plant growth can be met at the same time, provided that the simpleconcept of NFT is always remembered and practised. The result of these advantages is thathigher yields of high-quality produce are obtained over an extended period of cropping. Adownside of NFT is that it has very little buffering against interruptions in the flow, e.g.,power outages. But, overall, it is probably one of the more productive techniques.The same design characteristics apply to all conventional NFT systems. While slopes alongchannels of 1:100 have been recommended, in practice it is difficult to build a base forchannels that is sufficiently true to enable nutrient films to flow without ponding in locallydepressed areas. As a consequence, it is recommended that slopes of 1:30 to 1:40 are used.This allows for minor irregularities in the surface, but, even with these slopes, ponding andwater logging may occur. The slope may be provided by the floor, or benches or racks mayhold the channels and provide the required slope. Both methods are used and depend on localrequirements, often determined by the site and crop requirements.As a general guide, flow rates for each gully should be 1 liter per minute. At planting, ratesmay be half this and the upper limit of 2 L/min appears about the maximum. Flow ratesbeyond these extremes are often associated with nutritional problems. Depressed growth ratesof many crops have been observed when channels exceed 12 metres in length. On rapidlygrowing crops, tests have indicated that, while oxygen levels remain adequate, nitrogen maybe depleted over the length of the gully. As a consequence, channel length should not exceed10–15 metres. In situations where this is not possible, the reductions in growth can beeliminated by placing another nutrient feed halfway along the gully and reducing flow rates to1 L/min through each outlet. AeroponicsMain article: AeroponicsAeroponics is a system wherein roots are continuously or discontinuously kept in anenvironment saturated with fine drops (a mist or aerosol) of nutrient solution. The methodrequires no substrate and entails growing plants with their roots suspended in a deep air orgrowth chamber with the roots periodically wetted with a fine mist of atomized nutrients.Excellent aeration is the main advantage of aeroponics.Aeroponic techniques have proved to be commercially successful for propagation, seedgermination, seed potato production, tomato production, leaf crops, and micro-greens. Sinceinventor Richard Stoner commercialized aeroponic technology in 1983, aeroponics has beenimplemented as an alternative to water intensive hydroponic systems worldwide. Thelimitation of hydroponics is the fact that 1 kg of water can only hold 8 mg of air, no matterwhether aerators are utilized or not.Another distinct advantage of aeroponics over hydroponics is that any species of plants can begrown in a true aeroponic system because the micro environment of an aeroponic can befinely controlled. The limitation of hydroponics is that only certain species of plants cansurvive for so long in water before they become waterlogged. The advantage of aeroponics isthat suspended aeroponic plants receive 100% of the available oxygen and carbon dioxide tothe roots zone, stems, and leaves, thus accelerating biomass growth and reducing rootingtimes. NASA research has shown that aeroponically grown plants have an 80% increase indry weight biomass (essential minerals) compared to hydroponically grown plants.
Aeroponics used 65% less water than hydroponics. NASA also concluded that aeroponicallygrown plants requires ¼ the nutrient input compared to hydroponics. Unlike hydroponicallygrown plants, aeroponically grown plants will not suffer transplant shock when transplantedto soil, and offers growers the ability to reduce the spread of disease and pathogens.Aeroponics is also widely used in laboratory studies of plant physiology and plant pathology.Aeroponic techniques have been given special attention from NASA since a mist is easier tohandle than a liquid in a zero gravity environment. Passive sub-irrigationMain article: Passive hydroponicsPassive sub-irrigation, also known as passive hydroponics or semi-hydroponics, is a methodwherein plants are grown in an inert porous medium that transports water and fertilizer to theroots by capillary action from a separate reservoir as necessary, reducing labour and providinga constant supply of water to the roots. In the simplest method, the pot sits in a shallowsolution of fertilizer and water or on a capillary mat saturated with nutrient solution. Thevarious hydroponic media available, such as expanded clay and coconut husk, contain moreair space than more traditional potting mixes, delivering increased oxygen to the roots, whichis important in epiphytic plants such as orchids and bromeliads, whose roots are exposed tothe air in nature. Additional advantages of passive hydroponics are the reduction of root rotand the additional ambient humidity provided through evaporations. Ebb and flow or flood and drain sub-irrigationMain article: Ebb and flowIn its simplest form, there is a tray above a reservoir of nutrient solution. Either the tray isfilled with growing medium (clay granules being the most common) and planted directly orpots of medium stand in the tray. At regular intervals, a simple timer causes a pump to fill theupper tray with nutrient solution, after which the solution drains back down into the reservoir.This keeps the medium regularly flushed with nutrients and air. Once the upper tray fills pastthe drain stop, it begins recirculating the water until the timer turns the pump off, and thewater in the upper tray drains back into the reservoirs. Run to wasteIn a run to waste system, nutrient and water solution is periodically applied to the mediumsurface. This may be done in its simplest form, by manually applying a nutrient-and-watersolution one or more times per day in a container of inert growing media, such as rockwool,perlite, vermiculite, coco fibre, or sand. In a slightly more complex system, it is automatedwith a delivery pump, a timer and irrigation tubing to deliver nutrient solution with a deliveryfrequency that is governed by the key parameters of plant size, plant growing stage, climate,substrate, and substrate conductivity, pH, and water content.In a commercial setting, watering frequency is multi factorial and governed by computers orPLCs.Commercial hydroponics production of large plants like tomatoes, cucumber, and peppers useone form or another of run to waste hydroponics.In environmentally responsible uses, the nutrient rich waste is collected and processedthrough an on site filtration system to be used many times, making the system veryproductive.
 Deep water cultureMain article: Deep water cultureThe hydroponic method of plant production by means of suspending the plant roots in asolution of nutrient-rich, oxygenated water. Traditional methods favor the use of plasticbuckets and large containers with the plant contained in a net pot suspended from the centreof the lid and the roots suspended in the nutrient solution. The solution is oxygen saturatedfrom an air pump combined with porous stones. With this method, the plants grow muchfaster because of the high amount of oxygen that the roots receive. Bubbleponics"Bubbleponics" is the art of delivering highly oxygenated nutrient solution direct to the rootzone of plants. While Deep Water Culture involves the plant roots hanging down into areservoir of water below, the term Bubbleponics describes a top-fed Deep Water Culture(DWC) hydroponic system. In this method, the water is pumped from the reservoir up to theroots (top feeding). The water is released over the plants roots and then runs back into thereservoir below in a constantly recirculating system. As with Deep Water Culture, there is anairstone in the reservoir that pumps air into the water via a hose from outside the reservoir.The airstone helps add oxygen to the water. Both the airstone and the water pump run 24hours a day.The biggest advantages with Bubbleponics over Deep Water Culture involve increasedgrowth during the first few weeks. With Deep Water Culture, there is a time where the rootshave not reached the water yet. With Bubbleponics, the roots get easy access to water fromthe beginning and will grow to the reservoir below much more quickly than with a DeepWater Culture system. Once the roots have reached the reservoir below, there is not a hugeadvantage with Bubbleponics over Deep Water Culture. However, due to the quicker growthin the beginning, a few weeks of grow time can be shaved off. FogponicsMain article: FogponicsFogponics Fogponics is an advanced form of aeroponics which uses water in a vaporised formto transfer nutrients and oxygen to enclosed suspended plant roots. Using the same generalidea behind aeroponics except fogponics uses a 5-10 micron mist within the rooting chamberand as use for a foliar feeding mechanism. RotaryA rotary hydroponic garden is a style of commercial hydroponics created within a circularframe which rotates continuously during the entire growth cycle of whatever plant is beinggrown.While system specific vary, systems typically rotate once per hour, giving a plant 24 full turnswithin the circle each 24 hour period. Within the center of each rotary hydroponic garden is ahigh intensity grow light, designed to simulate sunlight, often with the assistance of amechanized timer.Each day, as the plants rotate, they are periodically watered with a hydroponic growthsolution to provide all nutrient necessary for robust growth. Due to the plants continuous fightagainst gravity plants typically mature much more quickly than when grown in soil or othertraditional hydroponic growing systems. Due to the small foot print a rotary hydroponic
system has, it allows for more plant material to be grown per sq foot of floor space than othertraditional hydroponic systems. SubstratesOne of the most obvious decisions hydroponic farmers have to make is which medium theyshould use. Different media are appropriate for different growing techniques. Expanded clay aggregateMain article: Expanded clay aggregateExpanded clay pebbles.Baked clay pellets, are suitable for hydroponic systems in which all nutrients are carefullycontrolled in water solution. The clay pellets are inert, pH neutral and do not contain anynutrient value.The clay is formed into round pellets and fired in rotary kilns at 1,200 °C (2,190 °F). Thiscauses the clay to expand, like popcorn, and become porous. It is light in weight, and does notcompact over time. The shape of an individual pellet can be irregular or uniform dependingon brand and manufacturing process. The manufacturers consider expanded clay to be anecologically sustainable and re-usable growing medium because of its ability to be cleanedand sterilized, typically by washing in solutions of white vinegar, chlorine bleach, orhydrogen peroxide (H2O2), and rinsing completely.Another view is that clay pebbles are best not re-used even when they are cleaned, due to rootgrowth that may enter the medium. Breaking open a clay pebble after a crop has been grownwill reveal this growth. GrowstonesGrowstones, made from glass waste, have both more air and water retention space than perliteand peat. This aggregate holds more water than parboiled rice hulls. CoirCoco Peat, also known as coir or coco, is the leftover material after the fibres have beenremoved from the outermost shell (bolster) of the coconut. Coir is a 100% natural grow andflowering medium. Coconut Coir is colonized with trichoderma Fungi, which protects rootsand stimulates root growth. It is extremely difficult to over water coir due to its perfect air-to-water ratio, plant roots thrive in this environment, coir has a high cation exchange, meaning itcan store unused minerals to be released to the plant as and when it requires it. Coir is
available in many forms, most common is coco peat, which has the appearance and texture ofsoil but contains no mineral content. Rice HullsParboiled rice hulls (PBH) decay over time. Rice hulls allow drainage, and even retain lesswater than growstones. A study showed that rice hulls didnt affect the effects of plantgrowth regulators.  Rice hulls are an agricultural byproduct that would otherwise have littleuse. PerlitePerlite is a volcanic rock that has been superheated into very lightweight expanded glasspebbles. It is used loose or in plastic sleeves immersed in the water. It is also used in pottingsoil mixes to decrease soil density. Perlite has similar properties and uses to vermiculite but,in general, holds more air and less water. If not contained, it can float if flood and drainfeeding is used. It is a fusion of granite, obsidian, pumice and basalt. This volcanic rock isnaturally fused at high temperatures undergoing what is called "Fusionic Metamorphosis". PumiceLike perlite, pumice is a lightweight, mined volcanic rock that finds application inhydroponics. VermiculiteLike perlite, vermiculite is a mineral that has been superheated until it has expanded into lightpebbles. Vermiculite holds more water than perlite and has a natural "wicking" property thatcan draw water and nutrients in a passive hydroponic system. If too much water and notenough air surrounds the plants roots, it is possible to gradually lower the mediums water-retention capability by mixing in increasing quantities of perlite. SandSand is cheap and easily available. However, it is heavy, does not hold water very well, and itmust be sterilized between use. GravelThe same type that is used in aquariums, though any small gravel can be used, provided it iswashed first. Indeed, plants growing in a typical traditional gravel filter bed, with watercirculated using electric powerhead pumps, are in effect being grown using gravelhydroponics. Gravel is inexpensive, easy to keep clean, drains well and will not becomewaterlogged. However, it is also heavy, and, if the system does not provide continuous water,the plant roots may dry out. Wood fibreWood fibre, produced from steam friction of wood, is a very efficient organic substrate forhydroponics. It has the advantage that it keeps its structure for a very long time. Wood fibrehas been shown to reduce the effects of "plant growth regulators."
 Sheep woolWool from shearing sheep is a little-used yet promising renewable growing medium. In astudy comparing wool with peat slabs, coconut fibre slabs, perlite and rockwool slabs to growcucumber plants, sheep wool had a greater air capacity of 70%, which decreased with use to acomparable 43%, and water capacity that increased from 23% to 44% with use. Using sheepwool resulted in the greatest yield out of the tested substrates, while application of abiostimulator consisting of humic acid, lactic acid and Bacillus subtilis improved yields in allsubstrates. Rock woolRock wool (mineral wool) is the most widely used medium in hydroponics. Rock wool is aninert substrate suitable for both run to waste and recirculating systems. Rock wool is madefrom molten rock, basalt or slag that is spun into bundles of single filament fibres, andbonded into a medium capable of capillary action, and is, in effect, protected from mostcommon microbiological degradation. Rock wool has many advantages and somedisadvantages. The latter being the possible skin irritancy (mechanical) whilst handling(1:1000). Flushing with cold water usually brings relief. Advantages include its provenefficiency and effectiveness as a commercial hydroponic substrate. Most of the rock woolsold to date is a non-hazardous, non-carcinogenic material, falling under Note Q of theEuropean Union Classification Packaging and Labeling Regulation (CLP). Brick shardsBrick shards have similar properties to gravel. They have the added disadvantages of possiblyaltering the pH and requiring extra cleaning before reuse. Polystyrene packing peanutsPolystyrene packing peanuts are inexpensive, readily available, and have excellent drainage.However, they can be too lightweight for some uses. They are used mainly in closed-tubesystems. Note that polystyrene peanuts must be used; biodegradable packing peanuts willdecompose into a sludge. Plants may absorb styrene and pass it to their consumers; this is apossible health risk. Nutrient solutionsMain article: Plant nutritionPlant nutrients used in hydroponics are dissolved in the water and are mostly in inorganic andionic form. Primary among the dissolved cations (positively charged ions) are Ca2+ (calcium),Mg2+ (magnesium), and K+ (potassium); the major nutrient anions in nutrient solutions areNO−3 (nitrate), SO2−4 (sulfate), and H2PO−4 (dihydrogen phosphate).Numerous recipes for hydroponic solutions are available. Many use different combinationsof chemicals to reach similar total final compositions. Commonly used chemicals for themacronutrients include potassium nitrate, calcium nitrate, potassium phosphate, andmagnesium sulfate. Various micronutrients are typically added to hydroponic solutions tosupply essential elements; among them are Fe (iron), Mn (manganese), Cu (copper), Zn(zinc), B (boron), Cl (chlorine), and Ni (nickel). Chelating agents are sometimes used to keepFe soluble. Many variations of the nutrient solutions used by Arnon and Hoagland (see above)
have been styled modified Hoagland solutions and are widely used. Variation of differentmixes throughout the plant life-cycle, further optimizes its nutritional value. Plants willchange the composition of the nutrient solutions upon contact by depleting specific nutrientsmore rapidly than others, removing water from the solution, and altering the pH by excretionof either acidity or alkalinity. Care is required not to allow salt concentrations to becometoo high, nutrients to become too depleted, or pH to wander far from the desired value.Although pre-mixed concentrated nutrient solutions are generally purchased from commercialnutrient manufacturers by hydroponic hobbyists and small commercial growers, several toolsexists to help anyone prepare their own solutions without extensive knowledge aboutchemistry. The free and open source tools HydroBuddy and HydroCal have been createdby professional chemists to help any hydroponics grower prepare their own nutrient solutions.The first program is available for Windows, Mac and Linux while the second one can be usedthrough a simple Java interface. Both programs allow for basic nutrient solution preparationalthough HydroBuddy provides added functionality to use and save custom substances, saveformulations and predict electrical conductivity values.The well-oxygenated and enlightened environment promotes the development of algae. It istherefore necessary to wrap the tank with black film obscuring all light.Organic hydroponics uses the solution containing microorganisms. In organic hydroponics,organic fertilizer can be added in the hydroponic solution because microorganisms degradeorganic fertilizer into inorganic nutrients. In contrast, conventional hydroponics cannot useorganic fertilizer because organic compounds in the hydroponic solution show phytotoxiceffects. CommercialSome commercial installations use no pesticides or herbicides, preferring integrated pestmanagement techniques. There is often a price premium willingly paid by consumers forproduce that is labelled "organic". Some states in the USA require soil as an essential toobtain organic certification. There are also overlapping and somewhat contradictory rulesestablished by the US Federal Government, so some food grown with hydroponics can becertified organic.Hydroponics also saves water; it uses as little as 1⁄20 the amount as a regular farm to producethe same amount of food. The water table can be impacted by the water use and run-off ofchemicals from farms, but hydroponics may minimize impact as well as having the advantagethat water use and water returns are easier to measure. This can save the farmer money byallowing reduced water use and the ability to measure consequences to the land around afarm.To increase plant growth, lighting systems such as metal-halide lamp for growing stage onlyor high-pressure sodium for growing/flowering/blooming stage are used to lengthen the dayor to supplement natural sunshine if it is scarce. Metal halide emits more light in the bluespectrum, making it ideal for plant growth but is harmful to unprotected skin and can causeskin cancer. High-pressure sodium emits more light in the red spectrum, meaning that it isbest suited for supplementing natural sunshine and can be used throughout the growing cycle.However, these lighting systems require large amounts of electricity to operate, makingefficiency and safety very critical.The environment in a hydroponics greenhouse is tightly controlled for maximum efficiency,and this new mindset is called soil-less/controlled-environment agriculture (CEA). With this
growers can make ultra-premium foods anywhere in the world, regardless of temperature andgrowing seasons. Growers monitor the temperature, humidity, and pH level constantly.Hydroponics have been used to enhance vegetables to provide more nutritional value. Ahydroponic farmer in Virginia has developed a calcium and potassium enriched head oflettuce, scheduled to be widely available in April 2007. Grocers in test markets have said thatthe lettuce sells "very well", and the farmers claim that their hydroponic lettuce uses 90% lesswater than traditional soil farming. AdvancementsWith pest problems reduced, and nutrients constantly fed to the roots, productivity inhydroponics is high, although plant growth can be limited by the low levels of carbon dioxidein the atmosphere, or limited light exposure. To increase yield further, some sealedgreenhouses inject carbon dioxide into their environment to help growth (CO2 enrichment),add lights to lengthen the day, or control vegetative growth, etc.