How do I use less water in the garden?
Severe drought is a dramatic reminder of the vulnerability of gardens that require lots of water to look their best. Garden technology has developed rapidly in recent times such that modern irrigation equipment makes it very easy to deliver large quantities of water at any time of the day or night. In such situations overwatering happens all too frequently, as inexperienced gardeners strive to make sure they have a verdant oasis in their yard.
Planning a waterwise garden
Thoughtful planning and design at the outset can cut the need for artificial watering to an absolute minimum. For instance, lawns require lots more water to look their best compared with most other types of plants. Why not eliminate lawn altogether unless there is a very good reason such as providing a play area for children. Low maintenance ground covers such as native violet (Viola hederacea) will survive and look good with minimal watering. Alternatively paving will not only eliminate the need for water but will also channel any rainwater runoff onto your garden.
To plan a truly waterwise garden a good trick is to select plants that come from drought prone areas of the world. The dry eucalypt forests of Australia, of course, are a good example, as are the semi-arid climates of Africa and America that feature succulent plants with the ability to store copious amounts of water in their leaves to get through lean periods. Drought tolerant foliages can take a number of forms such as being silvery, grey, leathery, succulent or hairy so look for these features when choosing plants for your garden. Grouping plants with similar foliages together is a very sound design principle that will ensure a harmonious look.
Most plants, and particularly trees and shrubs, can become acclimatised to less water to the point where artificial watering can be eliminated altogether. While it is very desirable to ensure that new plantings are watered in initially to help them over any transplant shock, once a plant is established you can gradually reduce artificial watering to zero over a period of a couple of months. Growth may be reduced by this strategy, particularly during dry periods, but if there is reasonable natural rainfall the plants will still perform admirably. It must be said that there are a few exceptions such as fast growing annual flowers and vegetables that must have constant water to give a reasonable result
Mulching is an obvious way to conserve moisture, however, it is important to select the right material and apply it so as to optimise the result. The coarser the material the better as large air pockets within the mulch create the most effective insulating blanket. Also choose materials that will not break down rapidly such as bark or woodchips or coarse gravel (such as scoria). The latter is particularly useful if there is a threat of bushfires. A depth of around 10 cm for your mulch will give the best water saving result also.
While it is possible to get away with not watering most garden plants artificially there are situations where there are compelling reasons to irrigate such as a hedge planting that is required for privacy and/or as a windbreak. Drip irrigation is by far the most efficient way to deliver water artificially where this is necessary. Various easily installed kits are now available and technology is steadily improving to make such systems easier to operate.
Water storing crystals
Water storing crystals are a powerful way of making the most of any water that goes into the soil. They are materials that come as opaque granules that swell as they absorb water and over a period of days the water is released back to plant roots as the soil dries out, thus creating an extra reservoir for your plants. Dig them in to the soil in recommended amounts when you are planting or fork them into the top few cm around existing plants.
Wetting agents are also useful to ensure that whatever water is around penetrates the soil evenly and soaks right in. A simple way to determine whether you need them is if water beads in droplets on the soil or potting mix surface when it is applied. This is particularly important for potting mixes that can become very hard to rewet if they dry out completely. Most wetting agents come in liquid form and are simply applied from a watering can.
Tip: A huge amount of water is wasted while waiting for hot water to flow through when it is required. Keep a container handy in the kitchen and bathroom to catch all the cold water that flows from your hot tap and use it to water potted plants around the house and patio.
Tip: The water that remains after boiling vegetables is chock full of nutrients. Drain it off, allow it to cool down and use it as a weak liquid fertiliser to nourish your pot plants. However, if you use salt in your cooking water it is best not used on the garden.