Heat waves put our gardens to the test. Lawns turning yellow, wilting flowers, stressed shrubs, trees losing their leaves prematurely… These reactions are often normal, but following a few best practices can help limit the damage.

The good news? If you take the right steps at the right time, your plants will get through the hot weather much more easily.

New Plantings: Special Attention

Plants planted this year or during the past two growing seasons are the most vulnerable to heat waves. Their root systems are still developing and do not yet allow them to draw water from deep in the soil.

Water less often… but more thoroughly

Shallow watering moistens only the top few centimeters of soil. As a result, the roots remain near the surface, where the soil dries out very quickly.

Instead, opt for slow, generous watering that allows the water to penetrate deeply. This will encourage the roots to grow toward the cooler layers of soil.

Water at the right time

It's best to water early in the morning. Temperatures are cooler, evaporation is reduced, and the plants can make the most of the water before the heat of the day sets in.

In the evening, watering is still a good option if you can't do it in the morning. However, avoid watering in the middle of the day, when the sun is at its strongest.

Keep the soil moist

A layer of mulch is one of the best ways to protect against the heat. It reduces evaporation, keeps the soil cooler, and limits the growth of weeds that compete for water.

Mature plantations: Trust in their ability to adapt

A well-established tree or shrub generally has a well-developed root system that enables it to better withstand periods of drought.

This does not mean that it does not need water, but rather that it is best to take action only when conditions warrant it.

Water deeply during long periods without rain

After several days of intense heat, a single, thorough watering at the base of trees and shrubs is much more beneficial than several small waterings.

The goal is to deeply moisten the soil so that the roots can have a sustained supply of water.

Avoid large sizes

A heat wave is already a source of stress for plants. Severe pruning requires them to expend additional energy to heal and produce new growth.

Unless you are removing a dead or dangerous branch, it is best to postpone major pruning until cooler weather.

How to Care for Your Lawn

It's normal for a lawn to lose its beautiful green color during a heat wave.

In fact, grass often enters a dormant phase in order to survive drought.

To help with recovery:

• Keep the cutting height at about 8 to 10 cm (3 to 4 inches).
• Never cut more than one-third of the grass's height in a single mowing session.
• Leave grass clippings on the ground when there aren't too many of them; they help retain moisture.
• Limit the frequency of mowing when growth slows down.
• If watering is permitted in your municipality, opt for deep, infrequent watering.

In most cases, a well-established lawn will naturally turn green again as cooler temperatures and rainfall return.

Flower beds

Some perennials and annuals may appear wilted during the hottest part of the day, only to regain their full vigor in the evening.

Before you intervene, observe their behavior.

To help them get through the heat wave:

• Remove wilted flowers to encourage new blooms;
• Maintain a good layer of mulch;
• Water the soil directly rather than the foliage;
• Pay special attention to potted plants, which dry out much more quickly than those grown in the ground.

The Most Common Mistakes

During a heat wave, some well-meaning actions can unfortunately do more harm than good.

In particular, avoid:

• water for a few minutes every day;
• water in direct sunlight;
• mow the lawn very short;
• Fertilize during periods of intense heat, as this stimulates growth that requires more water;
• forget to check the needs of newly planted trees, which remain the most at risk.

The best strategy is to promote deep root growth and minimize stress on the plants.

Newly planted trees and shrubs require closer monitoring and regular watering, while well-established trees, shrubs, and lawns generally have the resources they need to withstand a few days of extreme heat.

By following these best practices, your landscape will be much better prepared to withstand heat waves… and to regain its full vigor once temperatures become more moderate.