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Summer is here and with El Niño weather conditions upon us, we’re in for a hotter, drier season than normal. Help to heatproof your garden by choosing heat-resistant plants that are more likely to survive extreme weather conditions and nurture existing plants by protecting the precious soil in which they grow, maintaining as much moisture in the ground as possible.
Start by choosing plants that can take the heat and will cope when the climate takes a hot and dry turn. Barbara Wheeler, curator at Auckland Botanic Gardens, says a key way to identify suitable plants is to research where they naturally occur. “Plants from hot, dry climates will obviously cope well with those conditions in the home garden,” says Barbara. Good examples of these include New Zealand natives such as grasses, smaller leafed coprosmas, libertia, harakeke (New Zealand flax), Muehlenbeckia astonii (shrubby tororaro) and lancewood.
It makes sense that New Zealand natives that have evolved over thousands of years are more tolerant to our climate than introduced plant species. Studies have also shown native plants remove more carbon from the atmosphere than exotic plant species, meaning they’re better at helping us slow climate change*.
Make sure you choose the right native plant for your region. However, if you’re dealing with particularly hot, dry conditions, landscape designer Sandra Batley from Flourish (flourishgardens.co.nz) recommends sun-loving Phormium spp. (Dwarf flax varieties), Griselinia spp. (NZ Broadleaf), Oleria Paniculata (Akiraho) and Xeronema callistemon (Poor Knights Lily).
Non-natives that have evolved to cope with dry weather conditions include succulents – the perfect summer plant. Originating from arid places, their superpower is an ability to endure long periods of time without water, which they do by storing water in their fleshy leaves, stems and roots. This makes them a great option for outdoor pots, which can dry out quickly during hot periods. Sandra’s top succulent picks include sculptural Aeonium spp., Aloe spp. and Echeveria spp. If you want some flower power, try kalanchoes, which have vibrant pink, red or yellow flowers; sedums also produce pretty blooms.
Lock moisture into your soil by regularly applying a layer of mulch, rather than leaving it bare and exposed to the elements. Scott Bromwich of Daltons likens mulch to a blanket that keeps your soil moist and cool underneath. Don’t be stingy with it, either. “To achieve the best results, apply a generous layer of mulch, about 5-10cm thick,” he says. “Remember, it is a physical barrier so light layers will have little to no effect.”
Scott suggests using a bark-based mulch-wood product – this breaks down more slowly than pea straw, which needs to be reapplied more often. The golden rule for mulching is to water your garden well before applying it to lock moisture in. Use good-quality soil mixes as well. “Choose a garden mix that contains a wetting agent,” says Scott. “This ensures uniform wetting of the mix when watering and improves moisture penetration to plant roots.”
Instead of giving established plants in your backyard a light sprinkle of water often, opt for long, deep waterings a couple of times a week. This will encourage plants to send roots deeper into the soil and make them more resilient during drier spells (vegies and flowers will need more frequent watering).
“Check by putting your finger into the soil and see if the watering has moistened the soil to a decent depth (up to the first knuckle). If not, keep watering,” says Barbara. “Water in the early morning or late evening, or even overnight using a weeper or soaker hose. This will prevent all that water you’ve spent time applying being wasted, as it evaporates fast in the heat of the day.”
Create shaded areas by planting the ultimate sun umbrellas: trees. “There is really good research* showing street trees lower the ground temperature beneath them by several degrees and make cities much more pleasant places on hot days,” says Barbara.
Trees also have a process called transpiration where they sweat water vapour through pores in their leaves, decreasing the overall temperature by cooling down the surrounding air. Grow shade-tolerant plants beneath them such as ferns, clivias and renga renga lilies. When temperatures rise, you’ll have a green oasis where you can sit back on a deckchair or sun lounger and cool down.
Learn about all things gardening with our plant products and tips.
Photo Credit: Juliet Nicholas, Getty Images
