Many things we do to stay cool on a hot day, like turning up the air conditioning, contribute to a vicious cycle that exacerbates climate change and locks us into hotter days in the future. Running through sprinklers or relaxing in a shady garden helps keep you 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.
It’s a myth that you have to water your lawn every day in the summer. Even when it’s very hot and dry, watering deeper and less often leads to a healthier lawn. If you like your lawn lush, you can still save water while keeping it green. But when it’s too hot to play outside anyway, letting your lawn turn gold saves water for the heavy hitters in your garden. Shrubs and perennials provide food and shelter for heat-stressed wildlife. As well as helping birds and small mammals, the plants in your garden beds provide showy flowers that you can enjoy from inside the house.
Potted plants dry out quickly and may need water more than once a day in very hot weather. Moving the pots to shady areas can help them survive with less frequent watering. Even planted in the ground, the more delicate plants will benefit from a shady cover to avoid sunburn and withering. Specialty 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 scorching tender leaves and lowering temperatures slightly.
A thick layer of mulch will help keep the 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 such as frogs and lizards as well as insects that birds feed on.
No matter what you do, plants need more water at higher temperatures. Even a well-designed landscape that can survive a normal season without watering will need supplemental water in the event of 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 tap water, water with collected rainwater. Large-scale cistern systems can be a major investment, but even a simple rain barrel can be useful in areas where it rains occasionally in the summer. You can also collect gray water from inside the house to water plants outside. While a gray water system capable of capturing all of your home’s wastewater is a complex plumbing project, a few simple tricks can capture water during a drought. Try keeping a bucket in the shower or placing a tub in the sink to catch water from washing rice or rinsing dishes.
Regardless of your irrigation method, avoid watering during the hottest part of the day when water evaporates faster than the soil can absorb it. Most sources recommend watering early in the day so plants are well hydrated before temperatures rise. Evening or night watering is often discouraged to avoid waterlogged soils 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 a heat wave, temperatures can rise 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. As heat waves become more frequent, learn from your losses and replace lost plants with native species or drought-tolerant cultivars. If entire areas of your garden are dead (or if you’ve learned to live without certain sections of lawn), plan for the future by installing sustainable xeriscape landscaping. In the vegetable garden, plan ahead to use heat-tolerant varieties and use dry gardening next year. You can make short-term changes to your gardening habits during heat waves. But as extreme heat becomes a predictable part of summer, the most effective long-term strategy is to adapt to a changing climate.