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Six Signs of Heat Stress in Plants

Many plants can't handle long periods of high temperatures.
Six Signs of Heat Stress in Plants
Credit: J.J. Gouin - Shutterstock

We’re not the only ones struggling in this oppressively hot weather: Most common garden plants prefer temperatures ranging from 59°–86°F. In fact, they can start to show signs of heat stress when it’s 90°F or above for long periods of time. Here’s how to recognize the signs of heat stress, and how to help your plants recover.

The signs of heat stress in plants

According to the Oregon State University Extension Office, the signs of heat stress in plants include:

  1. Wilting: A lack of water pressure in the plant will cause it to droop

  2. Bolting: The premature flowering of plants

  3. Sunscald: Sun damage that can look like dried-out fruit, or sunken, hardened areas on the fruit surface; discoloration; blisters on the skin of the fruit; a watery area on the fruit

  4. Dry leaf edges: More common in plants with large leaves

  5. Blossom and fruit drop: The plant’s attempt to conserve energy

  6. Leaf rolling and cupping: The plant’s attempt to minimize its leaf surface area

How to help plants experiencing heat stress

Fortunately, many plants can recover from heat stress, and those that lost blossoms or fruits will likely produce more as the season progresses. Here are a few ways you can help your plants recover from the heat, also courtesy of the Oregon State University Extension Office:

  1. Watering: Give your plants a deep soak in the morning, unless the plant is wilted: in that case, water it right away

  2. Create some shade: Move containers into the shade; use umbrellas or hang sheets to create shade for plants in the ground

  3. Mulch your garden or flower beds: This will help the soil retain moisture, and will act like insulation, protecting the soil from extreme temperatures

For more information on heat stress, visit the Oregon State University Extension Office’s website.