Four gardening tips for hot weather

Posted in: Gardening by Janet Manning Published: 27 May 2023

Using water wisely to keep plants healthy is even more important in hot weather. Neither you nor your plants want to have to work hard in the heat. Janet Manning, a horticultural scientist, shares 4 tips: when to water, encouraging plants to adapt, how to protect them and keeping the garden cool.

1. Water in the morning

The morning is the best time for watering because that’s when your plants and soil are ready to take in water.

As soon as the sun’s up plants start using water, and if the soil isn’t fully wet, they’ll adapt to partially dried root zones by producing abscisic acid (ABA), which stimulates the leaves to close stomata slightly, therefore reducing water loss. By the time you start watering in the morning, there is both a soil moisture deficit to hold the water and an immediate demand for it from the plants, so reducing the water that’s lost to deep drainage.

Similarly by night fall, when photosynthesis stops and stomata close, the rootzone is left with a moisture deficit again to stimulate the ABA effect the next morning. By not watering at night you also avoid encouraging slugs, snails and mildew.

2. Train your plants to be drought athletes

Did you know that keeping your plants really well watered all of the time just encourages them to need more water? Instead, if you reduce the amount of water you use, without causing your plants to wilt, you’ll train them to be drought athletes.

Again it’s abscisic acid that is the reason behind this. ABA is produced by plant roots when they are partially dried, which makes the plant partially close the stomata and therefore reduce the water it needs.

We’ve got another blog about how to be more efficient with your watering to promote healthier plants and soil.

3. Put plants in the shade

This may be obvious but being in the sun is thirsty work.

With every hour of sunlight your plants use water, and during the summer solstice that’s nearly 17 hours. By putting them in the shade for part of the day the rate of photosynthesis will slow down, reducing the water they lose. Not only will your plants welcome the break, but so will you from having to water them so much!

You can put up a sunshade over your plants, move containers into a shadier spot, push containers together so they shade each other slightly, or throw a light fabric over them.

4. Big plants keep your garden cool

There are so many things to love about trees, shrubs and hedges. When it comes to managing water, they cool the garden and are the least likely to need watering themselves.

When it’s hot, big plants pump out moisture from their broad leaves through evaporation, which absorbs heat in the atmosphere. This cools the garden, along with the shade they provide. And in a dry spell, with their deep roots they can access moisture without being watered.