In very hot weather, when the evaporation from the leaves is greater than water uptake from the roots, plants get dehydrated just like we do.
Unlike us, they can’t go for a swim or go sit in the shade. Fortunately, there are some simple strategies to help our plants minimise heat stress.
When it’s hot and dry the best thing you can do for your garden is mulch, mulch and more mulch. A thick layer of mulch helps to conserve the water you put onto your plants and also helps them deal with the heat by keeping the root zone cool. Mulching also suppresses weeds so the plants have less competition for water.
Water when you get the most value out of it. In the early morning or late evening, the evaporation is at it’s lowest, the soil is cool and you get the biggest bang out of the least amount of water.
Plants susceptible to fungal diseases, such as lawns and tomatoes, should be watered in the morning so they are not left with water on their leaves overnight, allowing fungus to take hold.
Take care not to over water though; you can drown plants very quickly, while it takes much longer for them to die of thirst. So feel the soil, you can quickly asses the moisture level with your finger, if it comes out dirty with cool soil stuck to it, the soil is fine. If your finger is dusty and no soil is sticking to it, it is time to water.
Deeply water trees but don’t overdo it, water-logging trees can cause them as much stress as drying them out. A deep watering once or twice a week is usually sufficient.
Young trees also benefit from having other plants around them while they are getting established. This helps to create a humid micro-climate around them and less water is transpired through the leaves.
Planting trees in a garden bed protected by undergrowth is ideal. If you have an isolated tree in a lawn you can give it a helping hand by protecting it with shade cloth or hessian to create a humid pocket.
Other hints and tips:
- use a foliar spray of seaweed or fish emulsion to toughen the cell walls of plants
- place pots in saucers of water in the shade
- put shade cloth over veggies to give them a bit of shade
- if the leaves on trees and shrubs have browned off or dried don’t pick them off, they will provide protection for the new growth