Being Waterwise outside your home

Planning and general design principles

Soil improvement

Mulch

Soil wetting agents

Planning an irrigation system

Irrigation system installation

Maintaining your irrigation system

Keeping gardens and lawns Waterwise

Approximately half of all household water use is outside the home.  Climate change and growing demand for water means that water efficiency is more important than ever.  Rainfall in WA has been decreasing since the mid 1970s and our aquifers are falling as less water filters naturally into them.  Inflows into our dams continue to decline and although we have another desalination plant on the way, it is essential that each household with a garden plays their part to reduce their water use.

There are several ways you can plan and maintain your garden so that it will need less water, but still be a thriving, attractive and colourful place to be.

Would you like a beautiful waterwise garden like this?  Visit our Waterwise Hints and Tips page to find out how to create one.

Waterwise Help

You can either do it all yourself; employ a Waterwise Landscaper or Waterwise Irrigation Specialist; or do a mixture of both. The Waterwise Specialists can be found on our website or you can call the Waterwise Helpline on 13 10 39 to find one near you.

Planning and general design principles

When it comes to planning your design, you will need to consider:

  • Orientation, sun and shade, the prevailing winds and water run off.
  • Soil types, water holding capacity, compaction, water repellence and fertility levels.
  • Availability of alternate water sources like groundwater, greywater and rainwater.
  • Views both inwards and outwards and overall area available for the garden.
  • Utility spaces (clothes drying, compost and storage areas), outdoor living spaces (barbeques, seating areas) and special needs (vegetable garden, swimming pool etc).
  • Plant preference and design styles (native/exotic, formal/informal etc).
  • Maintenance expectations and available budget.
  • Maximising the use of non-planting treatments such as paving and mulches.
  • At the same time, be aware of excessive unshaded paving which can be hot and glaring.
  • Keeping planted areas dense and consolidated.  Sparse scattered plants are more difficult to water efficiently than ones that are in defined areas.
  • Keeping lawn for functional and aesthetic requirements.  Lawn should never be used as a 'filler'.
  • Choosing a lawn type that is water efficient and best suited to your soil.  Members of the Turf Growers Association can advise you on the most suitable type.
  • If you are establishing a new lawn or garden you may apply for an exemption for it to become fully established if you meet the criteria. 
  • Obtaining expert advice on irrigation from our list of Waterwise Specialists or call the Waterwise Helpline on 13 10 39.

  More information about watering exemptions
  

Soil improvement

The best soil improvers are those based on organic matter.  They increase the water and nutrient holding capacity while providing the raw material that supports active soil micro-fauna.  The healthy soil then promotes healthy plant growth.  It is important to improve the top 15 - 20 cm of soil where the feeder roots of plants will develop.  Animal manures, worm farm residue, bagged soil improvers and soil conditioners are all good sources of organic matter.  Mix them in equal parts with the soil prior to planting out.

Use these points as a guide:

  • Shrubs, groundcovers and climbers 30 cm in depth and up to half a metre across.
  • Trees 40cm deep and 1m across and bedding plants 25 cm deep for the whole bed.
  • Garden soils are just as prone to becoming non-wettable as are lawn areas.
  • A regular application of a soil wetting agent in Spring and Summer is recommended.

You can also refer to our 'Soil improvement' brochure available from the 'Hints and Tips' page.

Mulch

Whilst any mulch is better than none, some mulches are much better than others.  Look for a Smart Approved WaterMark Waterwise mulch, a list of these are available on their website at www.smartwatermark.info

Mulching is enormously beneficial for all plants. The mulch should be spread over the entire planted area to a minimum thickness of 50 mm.

Organic mulches are preferred because they:

  • Break down over time and feed the plants.
  • Improve the soil organic matter content as they break down.
  • Reduce evaporation loss from the surface.
  • Encourage earthworms and soil microbial activity.
  • Restrict weed growth. Any weeds which do germinate are easy to remove.
  • Prevent wind and water erosion.
  • Protect the roots from daily temperature fluctuations.
  • Improve the appearance of the garden area.

Mulch

Soil wetting agents

Many Western Australian soils do not absorb water well.  A soil wetting agent should be applied during the planting or laying process and again at regular intervals.  A typical indication that water is not penetrating the soil is brown patches appearing in lawns.  Soil wetting agents should be applied to sandy soils at the start of the Winter rains, in early Summer and again as recommended by the manufacturer. 

Planning an irrigation system

There are four basic principles of good irrigation and modern irrigation systems are both cheap and adaptable.  When properly designed and operated, they provide effortless and very efficient watering.  You can also look at our 'Your Guide to Good DIY Garden Watering' brochure on the 'Hints and Tips' page. 

Your planning should consider these things:

Flow and pressure:

No matter what the source of water is for any irrigation system, it is important to have the correct flow and pressure to ensure correct operation of the sprinklers and valves. Too low a pressure results in uneven distribution from the sprinklers and a lack of coverage of the watered area. Too much pressure results in misting and loss of water through evaporation before it has a chance to hit the ground. 

Alternate source:

Groundwater bores - If used responsibly and located away from the ocean, river systems and wetlands, bores can be an environmentally friendly way to keep your garden healthy and save you money. The Department of Water have identified areas suitable and unsuitable for bores in the Perth metropolitan region.  To find out if a bore is suitable for a property call the Waterwise Helpline on 13 10 39.

Mains supply:

It is law that a master valve be fitted to any mains operated system to isolate the irrigation from mains pressure when the system is turned off.  This master valve must be tested and stamped for it to be legally used.  Irrigation Specialists are able to supply these valves.

Lawn:

Turfed areas will command a major portion of your total water use.  Considerable savings can be made if you use emitters which provide coarse drops, preferably at a low trajectory.  These will minimise evaporation.  Gear drive sprinklers and impact sprinklers are best where large, regular areas are involved.  Pop-up sprays are appropriate for smaller areas of lawn.  Uniform distribution is a critical consideration in water saving.  To find out more, contact one of our Waterwise Garden Irrigation Specialists on our website. 

Garden:

It is the root systems of plants that take up water so they are the only part of a plant that needs to be watered.  Widely spaced plants are best irrigated with drippers or small under tree type micro-sprinklers.  Closely planted, smaller plants can be irrigated with micro sprinklers, where several plants will be watered by each sprinkler.  Sub irrigation systems can be adapted to water widely or closely spaced plants.

Specialty areas such as vegetable gardens and fruit tree areas also need separation.  In most cases, fruit trees and vegetable gardens need more water than average garden areas to ensure good production.

Irrigation system installation

This is another critically important stage, as changes are difficult to make later.

  • Detailed advice on installation is available from a Waterwise Irrigation Design Shop.  Follow the manufacturers' instructions carefully. In particular, do not 'economise' by allocating too many emitters to any one station; or placing pop-ups too far apart.
  • Once installed, lawn spray heads should be adjusted to throw the correct distance.
  • In the garden, drip or sub-mulch irrigation is recommened and can be installed progressively, as planting takes place.
  • Most garden emitters are designed to operate at low water pressures. Ensure each garden station is fitted with a flow reduction valve at the inlet.
  • Garden emitters such as drippers and greenhouse misters have fine valves and are easily clogged. Each station should incorporate an in-line filter.

Maintaining your irrigation system

  • For pop up sprinklers, a maximum of 15 minutes per station on your two watering days in Summer is sufficient.
  • During Winter, your irrigation system should be turned off.
  • You only need to water on one of your rostered days during Spring and Autumn, and only if it hasn't rained.
  • Set the start time to early morning, to reduce evaporation losses caused by sun and wind.
  • Program a separate watering frequency for each watering zone.
  • Set the run-time required to give your lawn a Standard Drink. Catch Cups are designed for this purpose, please call the Waterwise Helpline on 13 10 39 to find out where these are available from.
  • Set the run-time required for each of your garden Watering Zones. The objective of a dripper system is to supply a Standard Drink of 10 litres / m2 of ground beneath each plant's leaf canopy. In practice this means selecting a run time which will cater for the 'average' size plant on the line. Variable-flow drippers can then be used to fine tune watering to smaller or larger plants. Larger shrubs may need a number of drippers spread over the root zone. If low pressure sprinklers are required to water trees, they must be on a separate line to the drippers.
  • Ensure the settings adhere to the water efficiency measures for your area.

Keeping gardens and lawns Waterwise

 Watch the Garden Gurus video to help you maintain your Waterwise garden
  

Most gardens need regular maintenance to ensure they remain Waterwise.  Waterwise gardens are usually low maintenance but are never no maintenance.  Maintenance includes:

  • Topping mulch up regularly to keep a minimum thickness of 50 mm.
  • Only top dress lawns to even out bumps and hollows and then only use special top dressing mixes which contain organic matter.  Compost makes great organic matter. 
  • Applying soil wetting agents to both lawns and gardens on sandy soils on a regular seasonal basis.  Not promoting unnecessary growth, especially lush growth by using a lot of fertiliser.  Lush growth is more susceptible to attack by pests and diseases.  High fertiliser use also means high water use.  In most gardens plants are given far more nutrients than they can use or need.  Use slow release fertilisers for greatest efficiency and least pollution.
  • Controlling weeds which compete with desirable plants for available moisture.  A mulched surface makes weed removal easier.
  • Pruning excess growth from plants after they have flowered and or fruited to reduce their water needs.
  • Don't over water your lawn or garden and adjust the controller programme to ensure that watering frequency is correct for the season:
    • Pop up sprinklers a maximum of 15 minutes per station on your two watering days in summer is enough. 
    • You only need need to water on one of your rostered days in spring and autumn, and only if it hasn't rained.
    • All irrigation systems should be turned off during Winter.
  • Mowers should be set so that only one third of the leaf area is removed at any time.  This should leave a grass blade length of some 10 to 15 mm.  This amount of leaf shadows the soil surface and thus reduces evaporation loss.  Mower blades should be raised another 5 mm or so during Winter because the growth rate of warm season grasses slows down in cold weather. 
  • Thatch contributes to the development of non-wettable soils and should be reduced by a hard mowing in Spring or the use of a de-thatching machine.