Water-Saving Garden Products

Our climate is fantastic for gardening.  We can grow just about anything by improving our soil and supplying enough water to suit the plants.  Improving soil isn’t tricky; adding lots of smelly stuff like compost and manure usually does the trick.  But, with our current watering restrictions, many home owners are becoming concerned and even confused about how much water is enough and how to use the myriad of water saving products that are available. 

Assessing the layout and plantings of the garden as well as the reticulation system is of course the best place to start when looking to reduce the amount of water required.  Have plants been grouped with others that have similar water requirements?  Have they been planted so that they receive the correct amount of sun or shade?  Do the sprinklers water the garden and lawn and not the walls and paths, even on a windy day?

Some would have you think that to have a beautiful garden and lush lawn without using lots of water that a fortune needs to be spent on water saving products but this isn’t actually the case.  Every water-saving product available is very effective but they each have different jobs and not all are needed for all situations.  Work out the problem first and then choose the solution from the options below.

SOIL WETTING AGENTS
Soil wetting agents allow the water to soak into the soil rather than running off the surface ensuring that every drop is delivered to the roots of the lawn or the plants.

Many soils in WA are hydrophobic or water repellent meaning that the water is unable to penetrate the surface, causing it to run off or sit on the top until it has evaporated.  It is believed that this is caused by organic matter breaking down, leaving a waxy coating on the soil particles.  Wetting agents are like detergents that break down this waxy coating allowing the water to instantly penetrate into the spaces in between.  Most potting mixes will also become water repellent if they are allowed to dry out.

To test if a garden bed or potting mix is water repellent, take a container of water and pour it over the surface.  If the soil is hydrophobic, the water will pool on top instead of being absorbed quickly.

Wetting agents are available in liquid or in granular form.  Granular wetting agents can be spread by hand or with a spreader directly over the lawn, garden bed or pot but should be watered in immediately to make them active.  Liquid wetting agents can be applied using a watering can for small areas or in ready-to-use hose applicators for garden beds and lawns.

Applying wetting agents regularly to a garden bed and lawn is essential in almost all areas of WA.  Depending on the brand and the soil type, wetting agents will last from two to six months.  Mark on the calendar when the next application is due to ensure that the soil doesn’t become water repellent again before the problem is noticed.

WATER STORAGE CRYSTALS
The purpose of water storage crystals is simply to soak up water and then release it gradually during dry conditions.  They do not solve the problem of soils being water repellent.

Water storage crystals can absorb up to 400 times their weight in water and then release this over a period of up to 21 days.  They will continue to do this for many years.  Crystals should be soaked with water prior to mixing through the middle level of the soil. It does not get sprinkled over the surface or even close to the surface as this will mean that the moisture that is released is not in the root zone.  One tablespoon of crystals will absorb about a litre of water if left overnight.

Water storage crystals can be “loaded” with seaweed extract or fish emulsion instead of just water to promote strong root growth in plants.

Water storage crystals are useful when planting into pots and containers or for mixing into the hole when planting seedlings, potted colour, ornamentals or plants that require a higher level of water.

ANTI-TRANSPIRANTS
Anti-transpirants apply a protective polymer over the surface of leaves and stems which protects plants from heat, water loss, drying winds, sunburn, frost and transplant shock.

The invisible film is sprayed on and stretches as the plant grows, lasting up to 90 days and reducing water usage by 50%.  Not all plants require this treatment but it is fantastic in summer to protect those favourite plants that are vulnerable to drought, sunburn or wind damage or in winter to provide protection against frosts.

Prepare a tree or shrub for transplanting by watering well and then spraying with an anti-transparent several hours before moving.  This will ensure that the plant retains as much moisture as possible during the move thereby reducing any risk of transplant shock.  If planting shrubs, trees, seedlings and cuttings in very hot or very cold weather or simply to provide some extra protection to a new plant, spray with an anti-transparent at time of planting and again seven days later.

MULCH
Mulch stops moisture evaporating from the soil, reducing water loss by about 60%.  It also keeps the soil temperature constant and prevents weed seeds from germinating.

Every container and garden bed should have a layer of mulch that is renewed regularly.  There are organic and inorganic mulches available.  Organic mulches break down and add organic matter to the soil improving its structure and drainage.  It also promotes earthworm and microbial activity.

Pea straw and lucerne hay are organic mulches that are available by the bale and are easy to use and inexpensive.  They are particularly useful for vegetable gardens and around fruit trees and last several months before breaking down.  Do not be concerned if peas sprout from the straw; these can be cut and dug back into the soil adding bonus nutrients.  To spread across the surface of the bed, simply break the bale of straw or hay up into biscuits and lay it out like tiles.

Lupin mulch is high in nitrogen, improves the soil as it breaks down and will not blow away.  It is available by the bag or can be home delivered in a large bulk bag which covers an area of about 50m².  It is ideal for all garden beds including Australian natives and should be applied twice a year at a thickness of about 4cm.

Bark based mulches are also organic and come in various grades from fine to coarse.  Medium to coarse grade bark mulches are best as they don’t absorb any moisture and allow all rainfall and irrigation to penetrate through to the soil where it is needed.  Fine grade mulches tend to soak up the moisture like a sponge before it can get to the soil.  Bark mulches break down very slowly and last a long time but they can draw nitrogen out of the soil so overcome this by applying an organic fertiliser to the garden bed before a 4 to 7cm layer of the bark mulch.

Compost is too fine to be effective as a mulch.  Instead, use the compost as a soil conditioner by putting a layer of this underneath the layer of mulch.

Inorganic mulches include gravel, river pebbles, scoria and even coloured rubber that don’t break down at all.  These provide colour or texture to the garden whilst still reducing moisture loss from the soil.  They are applied at a thickness of about 4cm and look fantastic in formal raised garden beds or on top of pots.  In the long term they can begin to look messy if leaves or debris fall on to them or if planting holes are frequently dug in the area.

IMPROVING SOIL
Without good soil, it won’t matter how much water is applied to a garden, the plants just won’t thrive.

Exciting new products are available that can make a lasting difference to our sandy WA soils. By incorporating natural rocks or clay, these solutions enhance soil quality without breaking down over time. Although they may involve a higher initial cost, they’re a worthwhile investment for anyone looking to help their plants thrive in Perth’s heat.

In addition to the above, adding plenty of compost and manure will improve sandy soils by helping to retain moisture, increase microbial activity and provide nitrogen for the plants but will break down over time.

Clay soils also benefit from compost and manure as they help to open up the soil structure allowing the oxygen and water to move through.  Digging gypsum or lime through clay soils will also help but it is important to only cultivate these types of soil when they are just damp-dry and not wet.