Microclimate Gardening - South Australia


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Microclimate Gardening - South Australia

  1. 1. MicroclimateAustralia has a huge range of climates, and the temperature and rainfall of your area willlargely dictate what plants will thrive in your garden. In Adelaide, there can be significantvariation in climate from region to region across the city. In addition, local conditions canvary even within a backyard. Accurately assessing your garden’s microclimate will helpyou water effectively and plan your waterwise garden.Coping with climate  The placement of hard surfaces such as paving,Within Adelaide, temperature, wind exposure and paths or roads that may radiate extra heat;evaporation are quite different between the and/orcoastal strip, the southern and central suburbs,  Trees, shrubs and other windbreaks.the northern plains and the hills. Coastal areasare warmer in winter than inland suburbs, andcooler in summer due to sea breezes. Right plant, right placeEvaporation and temperatures drop with elevation You can make your garden more water efficientas you climb into the hills. The northern suburbs by understanding:are particularly exposed to hot summer winds  How your garden features create microclimates;because of the topography.  How to use your garden features to yourAdelaide gardeners have to contend with a advantage; andMediterranean climate with extremely hot, drysummers and cool moist winters. Elevation also  How to modify your garden features ifaffects seasonal temperature and rainfall patterns, necessary.with some areas falling into rain shadows, Each microclimate provides different growingparticularly in the eastern and northern parts of conditions for plants. Matching plants to thethe hills. conditions they require is a major step towardsWhile annual temperature and rainfall variations creating a healthy and waterwise garden.have an obvious impact on your plant choice and Expert gardeners are renowned for relishing thewater use, you should also be aware of the effect challenge of growing plants outside their naturalof your garden’s microclimate. You can greatly habitat – cold climate plants in warm climatealter the impact of heat and evaporation on your areas and tropical’s in cooler climates.garden and therefore reduce water needs by However, for the average gardener, this isn’tcarefully planning and implementing key changes. generally a good idea. Plants that are matched with climates, and with the microclimates that suitWhat is microclimate? them, will need less water and maintenance, grow better and suffer less stress. In Adelaide thisMicroclimate is the localised climate that occurs means choosing waterwise, hardy species sucharound your home. The aspect and the amount of as local natives, succulents and cacti,sun and shade you get in your garden, the Mediterranean plants such as olives, rosemaryprevailing winds and the slope will all create your and lavender and other low to very low water usemicroclimate. Your garden’s microclimate is species. Your local nursery is an excellent placeaffected by: to ask for advice, or consult some of the online Buildings and walls; resources listed in the ‘Resources’ section of the Fences and other structures; WaterRight webtool.
  2. 2. need to apply less water in this area than youSite orientation use in your north facing area.It’s critical to know which direction your garden  Planting shade tolerant, lush foliage plants orfaces, especially which way is north, because ferns that provide a sense of coolness, but thatthat’s the direction the sun comes from. The are still waterwise. There are many speciesposition of the sun in different seasons and the which are suitable, such as Blechnum ferns,patterns of sun and shade at different times of the birds nest ferns, cast iron plants andday will have a major impact on plant choice and Monsteriosa.water use.  Shelter vegetables in summer by creating aA sunny aspect is a bonus if you want to grow temporary shade structure using stakes, wireplants that require full sunlight, especially and shade-cloth. This can be rolled back onvegetables and fruit trees. However, you may milder days and replaced when the temperatureneed to use large quantities of water to maintain climbs.plant health. Consider drought tolerant plants forlarge areas with full sunlight. If you are growing Windmore sensitive plants in full sun, be sure to shadethem using shade-cloth or a pergola featuring a Adelaide’s climate varies from season to season.deciduous vine during the hot summer months. Particularly in the northern plains, summer’s hot, dry westerly and northerly winds reduce humidityYou can modify the impact of aspect, but and greatly increase water loss from plant leavesgenerally the northern side of your house will be due to transpiration, and from soil due tosunnier, warmer and more exposed to the evaporation.elements. So the best place for low water useplants is the northern side of your house. An The rate of plant transpiration rises with anexposed western side will also get the hot increase in temperature and wind speed, and aafternoon sun, creating high water demand unless decrease in humidity. Plants wilt much faster onyou plant very low water use plants in this hot days, especially when the hot, dry summerlocation. winds are blowing. A plant wilts in an attempt to close its stomates and reduce water loss, but this defence can be fatal if water is not applied.Using shade Northerly and westerly aspects can be particularlyShading plants that are sensitive or require extra exposed to these hot, dry summer winds.water is your best method to reduce water needs. Windbreaks can moderate the effect of wind.A plant in the shade can lose up to 50% less Taking note of the existing windbreaks in yourwater than one in full sun. Use shade, or design garden can help you plant appropriately andyour garden to create natural shade, so the accurately calculate different areas of yourgarden will be cooler and need less water by: garden’s water needs. When designing your Using trees, shrubs, windbreaks, climbing garden, creating windbreaks will shelter your plants, pergolas and screens to provide shade plants and also create a more pleasant for the garden and outdoor living areas. environment. Planting large trees that provide their own shady There are many different ways of creating a microclimate. Deciduous trees can be useful on windbreak. Living windbreaks such as hedges or the north side of the house to provide summer screening plants protect the garden from wind and shade but let in winter light. Deciduous vines create shade and privacy. In seaside Adelaide can be planted to cover pergolas that shade gardens windbreaks facing the coast also help your garden in summer but allow the sun in protect your garden’s plants from salt laden winds. winter. Some good waterwise species are If living windbreaks aren’t possible, use lattice, ornamental pears, crepe myrtles, grapes and screens, shade-cloth or pergolas to shelter plants. wisterias. Windbreaks should act as a filter rather than a Only planting medium to high water use and/or barrier, since a solid barrier will create an area of shade or semi-shade tolerant plants on the turbulence behind the windbreak. south or south-eastern side of the house, which is often shaded and moist. You will probably If you can’t moderate the wind, choose plants that tolerate the conditions. Plants with tough, hard
  3. 3. leaves, or silvery leaves often tolerate wind. Most the south side) favoured by low water use plantsAdelaide area native plants can tolerate the that like cooler conditions, such as Dianella andeffects of both heat and wind exposure, and are Birds Nest Ferns;worth considering if you want to create a gardensuitable to the local conditions. Visit theLandscapes Alive Sustainable Landscapes Plant Hard surfacesSelector for advice on plants that can tolerate Gardens are a mix of garden beds, borders andexposed conditions. Some examples are the lawn, and hard, dry surfaces such as paving,various Eremophilla species, Banksia species, driveways and pathways.New Zealand Christmas Bush (Metrosideros), Garden beds near paving or driveways thatRosemary and native Coastal Rosemary radiate heat will be warmer than those near turf or(Westringia). out in the open. Being near the road often adds heat to front gardens. This increase in radiantSlopes heat increases the rate of soil and plant water loss. Large areas of hard surfaces can createThe topography and slope of your block will affect watering hot spots that require effort to maintainthe microclimate by affecting drainage patterns. plant health.This causes wet and dry spots that will yourinfluence your planting schemes and irrigation Choose light coloured paving (and walls) thatregimes in different areas. absorb less heat to minimise this effect. Making paved areas more permeable to allow rain to seepNorth and west facing slopes receive more direct into soil and nearby plant roots can help savesunlight and are more affected by prevailing water. Make paths from organic and poroussummer winds than south facing slopes. material such as gravel, pebbles, woodchips,You can turn slopes to your advantage by placing sawdust or bark mulch, rather than using hardhigh water use plants in garden beds at the paving.bottom of sheltered slopes.On steep exposed slopes, use low water use Constant changeplants, including appropriate natives, succulentsor other tough, waxy leafed species. Remember, plants don’t stand still, and microclimate will always change with the seasonsYou can deliberately contour a garden to redirect and as plants grow or are removed.run-off from paths or driveways to where it isneeded or camber paths towards garden beds. Trees that cast increasing shade as they mature may affect your watering regime, or you may haveTerracing can help prevent water waste on to prune trees to let more light into your house orsloping blocks. onto your sun loving plants.Avoid planting lawn on slopes as this can lead towater loss from run-off. Instead, terrace an area touse as a lawn and surround it with well planted, Ground cover and dense plantingsprotecting garden beds. Groundcovers and densely planted shrubs and grasses are extremely useful in keeping weeds at bay and reducing the rate of water evaporatingBuildings from the soil. They also shelter the root system ofBuildings, walls, fences and other structures affect other plants, allowing a ‘cool root run’ which ismicroclimate in a number of ways: very important for the health of many plant They can radiate heat to create hot spots that species. In Adelaide, covering the ground surface may require additional watering; is of critical importance in creating waterwise gardens. Groundcovers, or “green mulches” can They may block the sun to create areas of be used to reduce overall water loss from the soil shadows and shade that require shade tolerant by reducing how much water is lost from your soil plants and less watering; through the impact of wind and sun. Densely plant House eaves may create relatively dry spots your beds and minimise the area of soil that is that don’t receive rain. This can create a hot and exposed. Ultimately this will create a garden that dry microclimate (on the north side) suited to is low maintenance and requires far less water cacti and succulents, or cool and dry shade (on than a sparsely planted one.