By Kate Wall
One way of reducing the water needs of our gardens is to grow plants which have low water needs. These plants are often described as drought tolerant as they are able to withstand long periods without water. Although these plants are able to cope without a lot of water they will usually grow better if they do receive regular water. This means they will do well during times when your garden receives regular rain, but will not die easily during drought.
Plants which are able to withstand dry conditions often have certain characteristics which help them save water, including:
There are many groups of plants which can be surprisingly drought tolerant. Salvias, ornamental grasses, geraniums, day lilies and agapanthus are all important plants in creating highly drought tolerant cottage gardens. Shrubs such as rhaphiolepsis have course leaves and are very hardy and continue to flower well in dry times.
Some of these plants do have weed potential, in part because they are able to withstand dry periods very well. By choosing low seeding varieties you can enjoy these plants without worrying about them becoming bushland weeds. Queen Mum™ Agapanthus orientalis ‘PMN06' PBR, Agapanthus orientalis 'Cloudy Days' PBR, Cosmic Pink™ Rhaphiolepis indica ‘RAPH02’ PBR and Cosmic White™ Rhaphiolepis indica ‘RAPH01’ PBR are low seeding varieties of agapanthus and rhaphiolepis which are all drought tolerant and beautiful high performing garden plants. When it comes to ornamental grasses, avoid planting the African pennisetums and instead seek out the wonderful native pennisetums. Purple Lea® Pennisetum alopecuroides ‘PA400’ PBR is a very beautiful low seeding variety. Many other native grasses are also wonderfully drought tolerant and attractive garden plants. Poa labillardieri ‘ESKDALE‘ PBR is a very beautiful native grass which is highly drought tolerant.
Many Australian natives are highly drought tolerant. Native plants are adapted to our climate, which includes regular drought. However, not all native plants are drought tolerant. In general, local native species will be best adapted to local climate conditions, and it can be valuable to include some local native species in your garden.
Natives plants from very different regions may not always suit your local climate, so regardless of their drought tolerance, these varieties may not succeed in your garden. In particular those that live in the subtropical and tropical regions of Australia with highly humid summers, will struggle to grow many of the native plants from southern and western regions where there is little summer humidity, regardless of drought conditions. In humid climates much greater care needs to be taken when selecting drought tolerant plants to ensure plants are both drought and humidity tolerant. The Velvet Kangaroo Paw Range are not only very drought tolerant but also has greatly improved humidity tolerance compared to other kangaroo paws. Aussie Rambler™ Carpobrotus glaucescens ‘CAR10’ PBR is a wonderful native ground cover which will not only tolerate extreme dry conditions but also high humidity, and flower continuously.
Plant breeding has provided gardeners with an enormous range of beautiful garden suitable native plants which are highly drought tolerant. Native plants which are garden suitable usually refers to their compact shape and improved flowering. Grevilleas, callistemons, eremophilas, lepidospermas, correas and westringias have all been bred to be available in various shapes and sizes making them ideal drought tolerant plants for Australian gardens. These drought tolerant natives not only look great in gardens in dry times but are also an important source of food for native birds and animals during drought.
Choosing lily pilly, callistemons or westringias for hedges over exotics can also greatly reduce the water needs of your garden. Westringias such as Ozbreed Aussie Box® Westringia ‘WES02’/'WES08' PBR are highly drought tolerant and make a perfect water smart alternative to box hedges. While lily pillies are not often thought of as drought tolerant plants due to their lush green nature, they are surprisingly drought tolerant. In very dry conditions they may drop leaves and look a little bare however this is a drought survival mechanism and they will re-leaf very quickly when water becomes available. They will stay greener longer and recover faster than many other exotic hedges.
Many of the iconic South African plants in the Proteaceae family such as proteas and leucodendrons are also highly drought tolerant, as are many of the Mediterranean herbs such as rosemary, sage, oregano, thyme and lavender. All of these plants come from climates with hot dry summers. This means they are highly tolerant of dry conditions but not tolerant of high humidity.
Succulents are another group of plants which have gained popularity due to their highly varied shapes and colours. They are also very easy care plants which prefer dry conditions so will thrive on neglect and low water. For a long time these were considered to have little to offer to the gardener but a huge variety of sizes and shapes are now available, allowing for very complex and beautiful gardens to be created using predominantly succulents. Succulents are also able to offer dramatic flowers which are visited by bees and birds. Sea Urchin™ Aloe hybrid ‘ANDsea’ PBR is a stunning feature plant for any style of garden with huge red flower spikes. The aloe hybrids are reasonably humidity tolerant in addition to highly drought tolerant.
When looking for low water use plants, it is a good idea to ensure they are planted into good quality soil which will not water log during wet times, as very few drought tolerant plants are also tolerant of wet feet.