71115_CTP_001-029revised_DJHNv6_03:71115_CTP_001-027 22/5/09 12:42 PM Page 6 Acknowledgments Introduction My thanks go to a number of people for their help with this edition and Australia is often called ‘the driest inhabited country’, yet for too long garden- ongoing support for this book in its various forms over the past 15 years.These include all at New Holland including Diane Jardine for ers have been trying to defy the climatic reality of this land—one which is far editing and Hayley Norman for the map drawing; Lauretta Zilles for pho- removed from the British model on which our gardens and gardening practices tography; Debbie Golvan; Jenny McSwain; Robyn and Frank Lewis; and Jimmie Morrison. The illustration on page 10 is based on that of the are largely based. The time has come to discard this ‘horticultural cringe’ and Bureau of Meteorology and is used with permission.Thanks to all who to make gardens that respond to the true nature of the Australian climate. helped with earlier editions and whose plants or gardens are photographed. In particular, a special mention to Lauretta, Natalie and Callan for their ongoing support and patience. In a country as dry as Australia it makes sense to design our gardens to the conditions. A waterwise garden Key to symbols used in this book can be as colourful and vibrant as any garden; Throughout this book plants are listed by their common name and then it just uses less water. alphabetically by their Latin name, then by their level of dry tolerance. Reduce lawn H High dry tolerance It is easy to create a garden that is waterwise and environmentally friendly, yet full of colour, interest and variety. All we have to do is to adopt six vital principles.These are: Group plants M Medium dry tolerance 1 Reduce areas of lawn Dry tolerant L Low dry tolerance 2 Group plants according to their water needs Did you know... By following the tips Maintenance G Water guzzler 3 Use dry-tolerant plants in this book you could easily cut your garden’s Mulch H High heat tolerance 4 Maintain the garden consumption of drinking water in half, or even 5 Use mulch more. Water efficiently M Medium heat tolerance 6 Water efficiently L Low heat tolerance Any one of these six vital principles will help save water, but if you can incorporate all six in your garden you will really begin to notice significant savings in your water bill.
71115_CTP_001-029revised_DJHNv6_03:71115_CTP_001-027 22/5/09 12:42 PM Page 8 8 Waterwise Gardening Introduction 9 The environmental benefits Reducing water use does not mean gardens should become One significant benefit of a waterwise garden is the protection of our deserts of pebbles sparsely planted environment. If we don’t curb our rising water consumption soon, with cacti. With a little imagination, authorities will need to create additional dams and weirs, which in turn careful planning and preparation you means altering natural watercourses and submerging large areas of can create an extremely colourful native vegetation. Saving water in the garden will help reduce the need garden with low water require- for new water storage facilities. ments. Such gardens can be formal Collecting and using rainwater in our gardens could provide up to or informal, modern or traditional, 40 per cent of our garden’s water needs, and is one positive way to and designed to fit in with the condi- reduce the amount of water we are taking out of our natural environ- tions of a particular location. ment. Some estimates also suggest that using ‘greywater’ in the garden Furthermore, designing a water- could reduce a household’s total consumption of drinking-quality water efficient garden does not rule out by up to 20 per cent. using water as a feature. Indeed, a Our current garden-watering practices result in large amounts of recirculating pump will use very little fertilisers and salts leaching into waterways, causing pollution, salin- water. The cooling effect of water ity and outbreaks of blue-green algae. Waterwise gardening can features adds to our enjoyment of an largely prevent this by eliminating the over-watering which flushes outdoor lifestyle in this hot, dry land. these materials into our groundwater.The use of soil improvers, such Water features bring a cooling effect to a as compost, can also help to bind these nutrients in the plants’ root The economic benefits garden, and are water efficient if the water zones. Practices such as composting not only improve the fertility is recirculated by a pump. and water-retaining capacity of our soil, but reduce the volume of Most areas of Australia now operate waste going into landfills. under a ‘user pays’ system for household water. This system is believed to better reflect the real cost of water. The horticultural benefits Although it differs a little between states and regions, it is generally based on a two-part system.The first is a ‘service fee’ for getting water to A waterwise garden requires less maintenance, not only because it uses your door.You pay this fixed amount on each water bill whether you use less water (which reduces the time you spend watering), but also the water or not.The second part is the ‘usage fee’—the more you use, because many techniques used to reduce water demands also reduce the more you pay. It is this second part where most households can save maintenance requirements in general. For example, reducing the size of money simply by reducing the amount of water used in the garden. an area of lawn reduces water use and results in less time spent It has been estimated that between one-quarter and one-half of all mowing. Using mulch reduces evaporation from the soil but also domestic water use is for gardens. The potential for reducing this reduces weed growth, and so on. amount—and your water bill—is enormous. The lower maintenance properties of a water- Did you know... wise garden make it an ideal approach for More garden plants commercial and industrial properties, flats and probably die from units, weekenders and holiday homes. over-watering than A waterwise garden is also a healthy garden. from lack of water. The soil is improved and plant stress is minimised through appropriate plant selection, maintenance and watering.
71115_CTP_001-029revised_DJHNv6_03:71115_CTP_001-027 22/5/09 12:42 PM Page 10 10 Waterwise Gardening Introduction 11 Main climatic zones of Australia (based on rainfall) desalination plants. Unfortunately there are serious environmental reper- cussions from desalination, including the disposal of the waste products and brine water which are by-products of the process. Desalination is Major seasonal rainfall zones of Australia also a huge consumer of electricity, therefore further adding to the greenhouses gases which are largely responsible for climate change. Weipa Kalumburu Katherine Kowanyama What the future holds Halls Creek Broome Normanton Our water supplies are under increasing pressure. Australia’s popula- Tennant Creek Townsville tion continues to grow and yet our water supplies are actually Telfer Mount Isa Mackay dwindling. Climate change means that for most parts of Australia there Giles will be higher temperatures leading to greater evaporation. Generally Newman speaking, rainfall will be reduced and when it does come it will be Wiluna Oondnadatta more often in heavy downpours that tend to run off the surface rather Geraldton than soak into the ground. Kalgoorlie-Boulder Cook Additional demands for agriculture and industry to service the expand- Coffs Port Augusta Dubbo Harbour ing population also put pressure on the little we have, and further impact Port Lincoln Mildura on the natural environment. The El Niño phenomenon is not always an Horsham accurate indication of when drought will occur or for how long. We need to start doing something immediately to conserve this most Orbost precious and finite of resources on which all life depends.We can all do Bureau of Meteorology Summer Dominant Summer Uniform Marked wet summer Wet summer and Uniform Rainfall Cape Grim our bit by saving water in the house and, in particular, in the garden.With and dry winter low winter rainfall Strahan the six vital principles of waterwise gardening explained in this book, we Winter Winter Dominant Arid Wet winter and low Marked wet winter Low Rainfall can create bright, attractive, economical and low-maintenance gardens. summer rainfall and dry summer Understanding when rain occurs in your area will help you plan your waterwise garden. What is El Niño? Where Australia’s water comes from El Niño is a phenomenon often associated with droughts. The waters off the western coast of South America are usually cool with high surface pressures. The air from Australia is the driest inhabited continent in the world: more than 70 per this area travels on the easterly trade winds across the Pacific Ocean towards the cent of the continent receives less than 500mm of rainfall in an average warmer tropical waters and lower atmospheric pressure north of Australia. The year. Many areas, too, have long seasons where little or no rain falls. strength of this circulation is measured by an index called the Southern Oscillation The majority of our water is collected from surface sources—typically Index, which is the pressure at Tahiti minus the pressure at Darwin. run-off that is collected and held in huge storage dams and reservoirs.The Occasionally, unusually warm waters off the South American coast disrupt the water is then piped from these catchments to major population centres. circulation, giving weaker trade winds and resulting in less moisture being carried Most Australian capital cities rely on such systems for their water, except over the ocean to Australia. When this happens and the Southern Oscillation Index is Perth (which relies heavily on groundwater) and Adelaide (which utilises negative, it is likely that some parts of Australia might have lower than average waterflow from the Murray River, catchment facilities and groundwater). rainfall and possibly drought. Increasingly, authorities are turning to desalination as a source of fresh water, with all mainland states actively considering or installing
71115_CTP_001-029revised_DJHNv6_03:71115_CTP_001-027 22/5/09 12:42 PM Page 12 Chapter 1 Water-smart garden design Most Australian gardens are not designed with water use in mind. This chapter explains the process of designing—or redesigning—a garden to make it more water efficient. Along the way it puts two principles of waterwise gardening into practice: limit areas of lawn and group plants according to their needs. Those contemplating making a new garden have the opportunity to apply the principles ‘from the ground up’, and get it right from the start. Long-established gardens can also be made much more water efficient, however, by making simple changes to the design. To design a waterwise garden you must take into consideration the peculiarities of your site. Basically, this means taking a critical look at various aspects of your garden, including existing features, proposed inclusions, the way you intend to use the garden and any other aspects such as the slope of the ground, soil type and, of course, climate. Work with your climate To design a garden that makes best use of the advantages of your site, and at the same time reduces the impact of negative factors, you need to understand the elements of climate that influence your garden. Climate is divided into three categories: macroclimate, mesoclimate and microclimate. Macroclimate is the climate of a large area, such as a met- ropolitan city or provincial district, while mesoclimate is the climate of a more specific part within that general area. Microclimate is the climate of small areas, such as those found within a property boundary. The macroclimate of your area will broadly influence your plant selec- tion and water use in the garden.Things to be aware of include average temperatures at different times of the year, periods of low rainfall, occur- rence of frost, proximity to the coast (and therefore salt-laden winds) and so on. Microclimate, however, has the most bearing on the layout of your Four-o’clock Flower garden, and this is particularly true for established houses and gardens.
71115_CTP_001-029revised_DJHNv6_03:71115_CTP_001-027 22/5/09 12:42 PM Page 14 14 Waterwise Gardening Water-smart garden design 15 Understanding your microclimate Windbreak planting Hot winds dry out lawns and gardens rapidly, and make your garden much Factors affecting microclimate include the orientation of the property to less enjoyable. A windbreak planting can reduce the impact of these the sun, the direction and temperature of the prevailing wind, the influ- winds.(It may also change the amount of sun getting to parts of the garden, ence of nearby buildings, topography, the amount of reflective surfaces, however, so bear in mind the effect this will have on plants in the vicinity.) and the spread and foliage type of existing trees. Observing these factors will help you to either take advantage of the circumstances or put in Trees for windbreaks place appropriate steps to overcome the negative ones. Monterey Cypress Cupressus macrocarpa H This sunny Yate Eucalyptus cornuta H and exposed Coral Gum Eucalyptus torquata H area is planted Norfolk Island Hibiscus Lagunaria patersonia H up with sun- Olive Olea europaea H loving plants. Aleppo Pine Pinus halepensis H Cork Oak Quercus suber H Peppercorn Tree Schinus molle var. areira H Sydney Golden Wattle Acacia longifolia M Golden Blackwood Acacia melanoxylon M Coast Banksia Banksia integrifolia M Silky Oak Grevillea robusta M The southern side of a house and areas underneath trees often have Coastal Tea Tree Leptospermum laevigatum M Norfolk Island a microclimate that is shady and less exposed to hot, drying winds. Brush Box Lophostemon confertus M Hibiscus While lawn won’t grow well in these places, they are often great spots Osage Orange Maclura pomifera M for shade-loving plants. Because such areas do not dry out so rapidly, Flaxleaf Paperbark Melaleuca linariifolia M they make a good watering zone for plants of low dry tolerance. New Zealand Christmas Tree Metrosideros excelsa M The north and west sides of the house are generally hotter and more Stone Pine Pinus pinea M exposed to the elements.This could be a good spot for a lawn or veg- Holm Oak Quercus ilex M etable garden, as these need plenty of sun. Lillypilly Acmena smithii L Sometimes you may be able to adapt the microclimate of your garden. For example, if your outside Coastal exposure sitting area is north of the house Gardens situated close to and you wish to create shade to the sea are often particularly make it pleasant in summer, the windy. This wind carries addition of shade sails or a timber salts onto plant foliage, pergola with a deciduous climber which not all plants tolerate. will help achieve this. Coastal gardens often have to contend This grape-covered pergola creates with high winds, and windbreaks can a shady sitting area north of the house. help reduce the negative effects.