Extreme summer heat can be as exhausting for our plants as it is for us. During a heatwave, vegetables, flowers, and container plants can quickly become stressed by high temperatures and dry conditions. Fortunately, a few simple strategies can help protect plants from heat stress and keep your garden productive all summer long. In this short video, we’ll share five tried-and-tested ways to help your plants stay healthy during hot weather.
How do you protect plants from extreme heat?
The best ways to protect plants during a heatwave are:
- Water deeply in the morning.
- Mulch to reduce evaporation.
- Avoid fertilizing.
- Provide afternoon shade.
- Harvest fruits and vegetables promptly.
5 Ways to Protect Your Plants From The Heat
Here are five major ways to help your plants cope with the heat this summer.
1. Water the Right Way
To figure out when to water your plants, check soil daily by pushing a finger into the soil. Water if it’s dry an inch or two below the surface. A deep soaking every few days is better than a daily sprinkle on the surface.
Water early in the morning while it’s still cool and evaporation is slow.
Work soil into ridges around plants to create bowls. Water into these and the ridges will prevent water running away over the surface, giving it time to soak in near the roots. Or sink old pots or bottles into the soil next to plants and water into these.
If you’re unable to water daily in hot weather, a drip irrigation system controlled by a timer is a good idea.
Keep a close eye on container plants. They may need watering more than once a day, especially in windy conditions. Make sure the water is being absorbed fully into the potting soil, rather than just slipping down cracks between the potting soil and the wall of the container. Pour until water runs out of the bottom of the container, and use pot saucers under containers to retain the water for longer.
Learn more about when and how to water your garden.
2. Reduce Evaporation from the Soil
After watering, mulch with organic material such as compost, leaves, or grass clippings to shade the soil, keep the root zone cooler, and reduce evaporation.
Shade the soil with a living mulch by planting densely and/or using plants like squashes that are vigorous or have large leaves.
3. Don’t Fertilize in Hot Weather
Adding nutrients prompts plants to grow more, putting them under more stress in hot weather. Plus, they’ll need even more water to process the fertilizer, too! Stop fertilizing when it gets above 85–90ºF or when plants roll up their leaves, drop their flowers, or stop producing new flowers.
4. Provide Shade
Use shade cloth or other fabric such as old bed sheets pinned onto frames or hoops to provide shade for plants.
Cool-season vegetables, for instance cabbage and lettuce, and fruits such as strawberries, will particularly enjoy shade from hot afternoon sun.
5. Harvest Sooner Rather Than Later
Harvesting fruits or leaves promptly will help save your plant’s energy. Harvest partially-ripened fruits such as tomatoes and finish ripening them in the kitchen to give your plants a break. Plants might slow down in hot weather, but yields should increase again once the weather cools.
Signs of Heat Stress and Solutions
| Heat Stress Symptom | Likely Cause | Quick Solution |
|---|---|---|
| Wilting leaves | Heat and moisture loss | Deep water early morning |
| Leaf scorch | Intense afternoon sun | Add shade cloth |
| Blossom drop | Temperatures above 85–90°F | Reduce stress, keep soil moist |
| Slow growth | Heat stress | Pause fertilizing |
| Dry soil | High evaporation | Apply mulch |
Frequently Asked Questions
Why do plants wilt in hot weather even when the soil is moist?
Plants can lose water through their leaves faster than their roots can absorb it during extreme heat.
Should I water plants every day during a heatwave?
Not always. Deep watering less often is generally better than frequent shallow watering, though containers may require daily watering.
Is it safe to fertilize plants during hot weather?
No. Fertilizing during extreme heat can increase plant stress and water demand.
What plants need shade during a heatwave?
Cool-season crops such as lettuce, spinach, cabbage, broccoli, strawberries, and young seedlings benefit most from temporary shade.
Does mulch really help in hot weather?
Yes. Organic mulch reduces evaporation, cools the soil, and helps retain moisture around plant roots.
Summer heatwaves can be tough on the garden, but a few simple steps can make a big difference. By watering deeply, mulching to conserve moisture, providing shade when needed, avoiding fertilizer during extreme heat, and harvesting crops promptly, you can help your plants stay healthy and productive through even the hottest weather. With a little extra care, your vegetables, flowers, and containers will be better equipped to weather the heat and bounce back when cooler temperatures return.
