How to Grow Tomatoes in Extreme Heat So They Keep Producing All Summer

Key Points

Tomatoes thrive in warm weather, but extreme heat can stress plants and reduce their ability to produce fruit.

Choose heat-tolerant tomato varieties, provide afternoon shade, and water early to help plants survive high temperatures.

Use mulch to retain soil moisture, avoid overwatering, and harvest early to prevent sunscald during heat waves.

As a summer crop, tomatoes are known for being extremely heat-tolerant. They’re even grown as perennials in tropical regions. So, if you live in an area where very warm weather sometimes strikes, you might assume there isn’t anything special you need to do for your tomatoes. But this is a bit of a misconception. Tomatoes do enjoy heat—to a point. When temperatures in your garden soar to high extremes, you might need to take steps to help your plants survive and continue to thrive.

Meet Our Expert

Angela Judd, certified master gardener, author of How to Grow Your Own Food, and founder of Growing in the Garden

Holly Ferrell, a horticulturist with training from the Royal Horticultural Society Garden Wisley and the author of The Tomato Grower’s Handbook

Jennifer Petritz, horticulturist, garden coach, and horticultural consultant specializing in small garden design

Related: How to Grow Tomatoes in Pots and Containers on Your Deck, Patio, or Porch

Choose the Right Variety

If you live in a climate where extreme heat is typically a summer reality, you can help put things in your favor by planting certain tomato varieties. “Smaller types are more reliable producers in hot climates where our seasons can be cut short by intense heat,” says master gardener Angela Judd. “They take less time to develop. A few of my favorite varieties are Sun Gold, Juliet, and Yellow Pear.” She also suggests seeking out varieties bred to fruit at higher temperatures. “I’ve had good success recently with Jolene tomatoes,” she says.

Pick the Right Place

Tomatoes need full sun—no question. But when growing tomatoes in a region with the possibility of extreme heat, you might consider providing some shade. “A little shade in the afternoon certainly won’t do any harm and can mean it’s less work for you as well,” says horticulturist Holly Ferrell. “The less water the plants lose in hot, sunny spots, the less watering you have to do to replace it.” She explains that as long as the tomatoes receive full sun for at least half the day, they’ll grow well.

Water the Right Way

The hotter it is outside, the more water your tomato plants will need. But it’s also important to water at the right time of day, which Ferrell says is early in the morning. “If you water in the hottest part of the day, some of what you put on is going to be lost straight away to evaporation,” she says. “Always apply water to the soil around the roots where it’s needed, not to the foliage, where the humidity can foster disease.”

But be careful not to overwater, as waterlogged soil can restrict oxygen flow to plant roots, says horticulturist Jennifer Petritz. Feel the soil around your plants and water when the top 1 to 2 inches are dry.

Add Mulch

Help your tomato plants retain moisture during dry spells with mulch. “Mulching is a great way to help preserve soil moisture,” says Ferrell. However, she cautions that mulching must be performed at the right time to maximize its effect. “If you mulch on dry soil, the mulch will act as a barrier against rain or water getting down to the roots. Make sure the soil is thoroughly damp before adding a mulch layer of 1 to 2 inches around your plants.” Ensure the mulch doesn’t touch plant stems, as this can cause rot.

Pick Fruit Early

If high temperatures are predicted and your tomatoes are close to ready for harvesting, consider picking them early and letting them ripen on the counter rather than outside on the vine. High temperatures can slow ripening, and the fruits can get sunscald. That said, if you forget to harvest during a heat wave, don’t worry too much. Petritz says leaves with sunscald can be pinched off.

Tips

Don’t always assume a wilting plant is dehydrated. “In hot, sunny conditions, plants will sometimes allow their leaves to fold downwards, even if they have plenty of water,” says Ferrell. “This is a natural process called sun wilt—plants use it to avoid losing too much water from their leaves in the heat of the day, and they’ll perk right back up again as the temperature drops in the evening.”

Use a Shade Cloth

If the tomato plants in your garden don’t receive any natural shade from trees or buildings, you can create it with shade cloth during periods of extreme heat. Shade cloth comes in a variety of strengths, often ranging from 30 to 50 percent sun blockage or more. In very hot climates, shade cloth hoops can be installed semi-permanently. These hoops are flexible, arched supports that stake into the ground; the cloth is draped over the hoops as needed to shield plants from the hot sun.

Monitor for Pests and Disease

Healthy plants are better at surviving heat stress than plants that are already weakened, so keep an eye on your tomato plants throughout the growing season for common pests, like tomato hornworm, and diseases, such as early or late blight, white mold, and canker. If you think your plant is suffering from a pest infestation or disease, identify the issue and treat it accordingly to avoid plant death.

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