A lot of the things we do to stay cool on a hot day, like cranking up the AC, contribute to a vicious circle exacerbating climate change and locking us into more hot days in the future. Running through the sprinklers or relaxing in a shady garden helps you stay cool without air conditioning. But sprinklers and gardens use a lot of water. Keeping your garden green during a heat wave without depleting water supplies isn’t always easy, but it is possible.
Reduce Thirst
It’s a myth that you have to water your lawn daily in summer. Even when it’s very hot and dry, watering more deeply less often leads to a healthier lawn. If you love your lush lawn, you can still save water while keeping it green. But when it’s too hot to play outside anyway, letting your lawn go gold saves water for your garden’s heavy lifters. Shrubs and perennials provide food and shelter for wildlife stressed by the heat. Besides helping birds and small mammals, plants in your garden beds provide showy blooms you can enjoy from inside the house.
Potted plants dry out quickly and may require water more than once a day when it’s very hot. Moving pots into shady areas can help them survive with less frequent dousing. Even planted in the ground, more delicate plants will benefit from shade cover to prevent sunburn and wilting. Specialized garden fabric can be draped directly over plants, but you can also hang a bed sheet over a trellis or stakes to keep sunlight from burning tender leaves and to reduce temperatures slightly.
A thick layer of mulch will help keep roots cool and slow the evaporation of water from the soil. For best results, use an organic material like coarse wood chips. Mulch also provides a shady refuge for beneficial wildlife like frogs and lizards as well as the insects that birds feed on.
Smart Watering
No matter what you do, plants need more water in hotter temperatures. Even a well-designed landscape that can survive a normal season without watering will need supplemental water in a drought or heat wave. Spraying plants with a hose or running sprinklers uses a lot of water, much of which is wasted through runoff and evaporation. Drip irrigation using soaker hoses or tubes will deliver water directly to the soil around the plants much more efficiently.
Instead of drawing water from the tap, irrigate with collected rainwater. Large-scale cistern systems can be a major investment, but even a simple rain barrel can be helpful in areas with occasional summer rains. You can also collect gray water from inside the house to water plants outdoors. While a gray water system that can capture all the wastewater from your house is a complex plumbing project, some simple hacks can catch water during a dry spell. Try keeping a bucket in the shower to or set a tub in the sink to collect water from washing rice or rinsing dishes.
Regardless of your method of irrigation, avoid watering during the hottest part of the day, when water will evaporate faster than the soil can absorb it. Most sources recommend watering early in the day so that plants are well hydrated before temperatures rise. Evening or nighttime watering is often discouraged to avoid waterlogged soil and fungal diseases on wet leaves. If you use drip irrigation, you don’t have to worry about wet leaves. And during a drought or heat wave, temperatures can get very high even early in the day. On those hot days, standing water is unlikely to be a problem even at night. When conditions are extreme, watering in the evening is probably best.
Learn From Loss
Brown lawns bounce back, but sometimes more sensitive plants don’t survive the heat. Since heat waves are becoming more common, learn from your losses and replace lost plants with native species or drought-tolerant cultivars. If whole areas of your garden died off (or if you learned to live without some sections of lawn), plan for the future by installing sustainable xeriscape landscape designs. In the vegetable garden, plan ahead to use heat tolerant varieties and using dry gardening next year. You can make short-term modifications to your gardening habits during heat waves. But as extreme heat becomes a predictable part of summer, the most successful long-term strategy is to adapt to a changing climate.