How to Protect your Plants in Hot Weather
As any gardener will tell you, summertime is the season when all our efforts in the garden are rewarded. Warm-season crops such as tomatoes and peppers seem to grow right before our eyes, and the beautiful sunshine triggers flowering plants to burst into life. But what about when things get too hot – is this a problem for our plants? And how can we protect our gardens during heatwaves and prolonged drought?
While warmth and sunlight are essential for plant growth, many plants will struggle during periods of extreme heat. At temperatures of 90F and above, growth will become stunted and plants will start to show signs of stress. When the thermometer creeps above 104F, plants can be so badly damaged that they fail to recover when the weather cools down.
Where I live, we frequently experience temperatures of 104F and above during the summer. So, if you live in a region prone to heatwaves, you’ll be glad to hear that I’ve got plenty of tricks up my sleeve to help your plants become more resilient in the face of extreme temperatures!
1. Watering
When a heatwave is forecast, it is helpful to increase your watering schedule before hotter weather arrives. The rate at which leaves release water to the atmosphere increases as temperatures rise, and the roots need ready access to moisture to prevent the plant from wilting. This is particularly important for summer fruiting crops like tomatoes, zucchini, and cucumbers, as they have shallower root systems and large amounts of leafy growth.
Although splashing water on leaves is generally regarded as a bad idea, during a heatwave this tactic may well save your crops. Plants can absorb moisture through specialized openings on the leaves, so by creating higher humidity levels we can make our plants more resilient to heat stress. If extremely high temperatures are forecast, lightly water your plants from above early in the morning to increase humidity levels.
2. Shade
Protecting your plants from direct sunlight is one of the best ways to reduce the risk of heat stress. In hotter climates, it is a good idea to grow plants that are susceptible to high temperatures in an area where they are partially shaded during the day. When you consider that the shade cast by a tree canopy can reduce temperatures by 11-19F you start to realize why food forest gardens are becoming so popular.
However, forest gardening doesn’t work for everyone, and some plants require full sun on all but the hottest days. For these areas of the garden, rig up temporary shade netting during the peak summer period to protect against excessive heat.
3. Mulch
Mulch is pretty much the key to solving every garden problem, helping to boost soil health, suppress weeds, and, most importantly of all, improve water retention. A generous layer of mulch creates a barrier between the heat of the sun and the soil surface, helping to keep plant roots cool and moist. Mulch also reduces the rate at which water evaporates from the soil surface.
For the best results, apply a 2-3” thick layer of mulch under your plants, taking care not to pile it up against the base of the stem. Good mulches for hot climates include wood chips, shredded bark, leaves, dried grass cuttings, pine needles, and well-rotted compost. Sheets of cardboard held down with rocks can also work well, but remember to leave sufficient gaps to allow for watering.
4. Take a break from plant maintenance
Plant growth will naturally slow down during a heatwave, and your plants will not thank you for too much interference! Although some parts of your plants may look scorched, it is best to leave these in place for the time being. Pruning away damaged areas will expose new growth to scorching sunlight, leading to further damage. This is also a bad time to apply fertilizer or any type of pest control treatment, so hold off on these until cooler weather returns.
The only maintenance I would recommend during a heatwave is to harvest tomatoes, cucumbers, zucchini, and other warm-season crops promptly. This reduces pressure on the plants, enabling them to focus their energies on surviving rather than crop production. Then, when temperatures return to normal, your plants will be in the best possible condition to thrive all summer long!