Do's and Don’ts for Gardening in a Heat Wave

During increasingly common heat waves in summer, temperatures can soar, making it a challenge to maintain a healthy garden.

When we have designed our gardens carefully, taken the right approach for where we live, and chosen the right plants for the specific growing conditions, we are far less likely to encounter problems.

But planning and preparation now won't help much during a current heat wave. So what should you do, no matter the present situation in your garden, to make sure that your favorite plants and key crops survive extreme weather conditions?

DO: Mulch, mulch, and mulch some more

Protecting the soil is one of the most important things to do in a heat wave. Bare soil can overheat more easily, killing off the beneficial soil life upon which many of our growing efforts depend.

Covering the soil with either plants themselves or with organic mulches helps us to keep the soil temperature down, and to maintain moisture levels in the soil by reducing evaporation. With organic mulches covering the soil, less moisture will be lost from the soil and there will be more available for the uptake of the plants you grow.

Do: Create shade to reduce air and soil temperatures for plants

When it is extra hot, even plants that love full sun most of the time may need some shade to reduce stress. In full sun, plants will typically use and lose more water than they do in the shade. So increasing shade cover during extreme temperature highs can often be beneficial.

You might increase shade through additional planting or through shade netting or man-made structures. Deciduous trees can often be beneficial, of course, because they provide shade when it is most needed in summer but lose their leaves and allow more sun through during the coldest part of the year.

DO: Set up sustainable watering systems

Of course, water can often be a problem in a heat wave. You may often find that during hot spells, water from usual municipal sources is in shorter supply. All the more reason why you should take matters into your own hands and set up sustainable water harvesting and watering systems on your property.

Ideally, you should have a good rainwater harvesting system in place. And should have spent some time thinking about how you can catch water on your property and keep it around. Even if you have yet to implement such a scheme, you can set one to be ready for when it rains once more.

In the meantime, you can also make sure that you use water more wisely, whatever the source. Set up irrigation systems to make sure plants get the water they need and that you are not wasting fresh water in your garden.

DON'T: Water little and often

One of the biggest mistakes you can make during a heat wave is to water frequently but shallowly. If you water little and often, this can encourage plants to develop shallower roots, which unfortunately reduces their resilience and can leave them far more vulnerable to hot and dry conditions.

Instead, it is important to water well and deeply each time that you water during a heat wave, leaving it longer between waterings but watering well when you do so. This encourages plants to develop deeper roots and gives them greater resilience for the future.

DON'T: Splash water around

Water should always be used wisely but especially so during a heat wave. Do not splash water around by watering from above. Make sure that you always direct water to where it is actually needed, in the soil close to plant roots.

Watering from above and getting water on the foliage, flowers, and fruits of plants not only potentially wastes a lot of water, it can also lead to problems for the plants themselves. Water on the above-ground portions of the plant can increase the chances of sunburn and also make it more likely for fungal diseases to take hold while plants are already stressed by the hot conditions.

DON'T: Allow overcrowding to occur

Overcrowded conditions, with too congested or competitive plants, can also increase stresses in your garden, especially during a heat wave. So keep on top of weeds and pruning, and if necessary, take plants out to reduce competition and increase airflow around your plants. This can reduce stress on your plants and help them to overcome challenging conditions.