Hot weather is the enemy of tomatoes

Hot temps, especially inland, will begin to ramp up as summer comes on. 

Hot summer temperatures can bring your tomato plants to a stop. And your plants get especially hot if they are planted next to a block wall, stucco wall, are in containers on a cement patio, etc.  

The surface temperatures radiating back off your patio/backyard dirt can reach 110-120 degrees. It can be brutal.  

When temperatures hit 85 to 90 degrees or so and nights are above 75 degrees or so, your tomato plant may go into survival mode until temperatures come back down. Plants may fail to produce pollen or fail to pollinate and the blossoms will simply drop off until the temperatures come back down.

Thermometer reading 123 degrees on patio near tomato plant
123 Degrees is the surface temperature of the patio on a 91 degree day.

C:\Users\Dave\Pictures\1-AAA My Pictures-official 2004 forward\111 Tomatoes---all history\91 degree day 3pm OK\Heroes\P1020024.JPG
Same 91 degree day, under 3 to 5 inches of straw your temperature will be 90 degrees or lower.

Shade helps

If you are in an area that will get some of that hot afternoon sun bearing down on your tomatoes, it helps to make some shade for that after 2 p.m. sun if you can. Shade cloth, for example, works well. Using 50% shade cloth, cut strips about 2 feet wide and 6 feet tall and hang on cages to shade the after-2 p.m. hot blistering sun. That sun can also scald your un-shaded tomatoes, giving them a sunburn.

If you see that your tomatoes are getting sunburned, sometimes it’s best to pick them a little early and let them finish ripening inside. When it gets really hot many tomato plants stop producing red pigment; instead of turning red, they will ripen an orange color.  

Mulch….helps lots in hot weather

For your tomatoes in the ground or in raised beds, Put a 3-5 inch-thick mulch layer around tomato plants. I use straw. This helps keep the top layer of soil cooler and prevents excessive evaporation of water.  See post on “Mulching.”


Keep that soil moist. Use that premium potting soil. Hot weather brings more evaporation. Use a moisture meter and don’t be surprised if you need to water daily. A mature tomato plant will use 2-3 gallons of water daily even in cooler weather. Pests and diseases in a warm soil wake up and thrive. Keep your plants watered and healthy so they can fight off the pests and diseases until those tomatoes ripen.   

Planting new plants in hot weather

Choose a heat tolerant variety. Heat tolerant plants will be labeled as such. They have names like Solar Fire, Heatmaster, Summer Set, Phoenix, etc. My favorite is probably Phoenix. These have been developed to produce tomatoes in 90 degree weather. If you are on the coast and do not experience excessive heat, you can plant normally; you don’t need heat tolerant plants.

On the left is Solar Fire and on the right is Heatmaster. Both are heat tolerant tomato plants 

You are welcome to share this information with others—clubs—perhaps share this with your general membership to include those that could not attend the lecture, family, friends, etc. 


Dave  “The Tomato Guy”