12 Ways To Keep Your Plants Alive During A Heatwave

Extremely high temperatures during a heatwave can place many plants under so much stress that they may or may not recover. The stress also leaves them vulnerable to plant diseases and pests. 

When temperatures climb above 90 degrees for more than an hour or so, plants experience excessive water evaporation through the pores of the leaves faster than the roots can absorb water. The leaves of the plants wilt from the heat stress. Just like humans, plants can also become sunburned from extended exposure to direct sunlight. Plant sunburn appears as discolored leaves and stems and scorched edges.

We’ve put together 12 ways to protect your plants during a heatwave and help them recover. Don’t forget to keep yourself protected and hydrated, as well!

Check The Soil Before Watering

Along with scorched and droopy leaves, the best way to tell if a plant needs water is to check the soil. Use a moisture meter or your finger to determine if the soil is dry two inches before the surface. If it is, it’s time to water. Container-grown plants need extra attention to determine a watering schedule. Depending on the size and type of container, twice-daily watering may be needed to keep plants healthy. 

Water Deeply

If you water for just a few minutes every day, plants will develop shallow roots that won’t stand up to extreme heat. It’s much better to water less often but water deeply so the soil is wet at least three inches deep. In general, gardens need around 1.5 inches of water weekly during heatwaves with little or no rain. That’s about one gallon of water per square foot of garden space.

Water In The Early Morning

Water plants during the early morning hours so that plants are fully hydrated before the highest temperatures of the day. Early morning watering also gives the foliage plenty of time to dry quickly to prevent disease.

Water Wisely

Plants are stronger if they absorb moisture and nutrients through the soil. Use drip irrigation, soaker hoses, or spot watering by hand so water reaches the root system. Use a timer on your irrigation system or set one on your phone to avoid overwatering which can also weaken plants. Avoid overhead sprinklers, if possible. They can cause water to evaporate before it ever reaches the roots, wasting water.

Banish Weeds

Weeds compete with desirable plants for moisture and nutrients. Keep vegetable gardens and flower beds weeded to keep heat-stressed plants stronger.

Mulch, Mulch, Mulch

Mulch helps lower soil temperatures and retain moisture longer. Add two to four inches of organic mulch around plants. Don’t make a mulch volcano around the stem of the plant which can cause water run-off. Leave a gently sloping well for a healthy plant.

Monitor Radiant Heat

Plant beds next to hardscapes—driveways, patios, walkways—are subjected to radiant heat and are often the first plants to show heat stress. Be sure they receive plenty of water.

Provide Some Shade

Even sun-loving plants may need some shade to make it through a heatwave. This is especially true for container plants. It’s a good idea to monitor the sun and move containers out of direct sun during the hottest times of the day. Use shade cloth structures to help reduce air temperatures and sunburn on tender or newly planted areas.

Deadhead to Conserve Energy

Plants want to survive which is why many expended lots of energy developing seed heads after they bloom. Deadheading spent blossoms will help the plants conserve energy so they will bloom more profusely once the heat has subsided.

Stop Fertilizing

Adding more fertilizer is not the answer to keeping plants healthy during a heatwave. Even with the extra nutrients, it takes lots of energy to put out new growth during high temperatures. Wait until it is a bit cooler to apply fertilizers.

Harvest Fruit Early

Harvest vegetables as soon as you can to help the plant save energy. Those small pods of okra and tiny, tender summer squash will be extra tasty and won’t create a moisture demand on the plant to grow them larger.

Delay New Plantings and Propagation

Adding new plants, dividing, or transplanting plants should be delayed until temperatures return to normal. Disturbing plants creates stress and the addition of high heat may be the death knell.