Why You Should Wait to Plant Tomatoes

Yes, it feels like summer already. 

Yes, I know your tomato seedlings are burning a hole in your pocket. 

No, it’s not a good idea to plant yet. 

The reason to wait

Tomatoes cannot survive a frost. Not even a “slight” frost. Even temps below 50°F make tomatoes unhappy.

March 12 is the official average last frost date for DFW. This means that frosts can happen before this date and after this date. 

Starting around March 8, I watch the weather forecast like a hawk. If there’s any slight risk of frost, I push back planting my tomatoes. I never plant before March 12.

Any spring temperatures near or below 40°F are within the range of temps when frost can occur. (For nerdy explanation of this phenomenon, see below.)

Don’t worry. As long as you get your tomatoes in before April 1st, you’re fine. There’s no need to risk dead tomato plants by rushing. 

Already planted? 

If you already planted your tomatoes, you will need to cover them if the weather forecast predicts temperatures near or below 40°F.

More tomato help

If you need more help with growing tomatoes, my Trouble-Free Tomatoes Class is available. Learn how to grow blue ribbon tomatoes, and get unlimited additional help from me with your tomato queries. Learn more about enrollment here. 

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Frost explained

Frost happens when the temperature at ground level drops below 32°F, causing moisture in the air to condense and form ice crystals on surfaces, even if the air temperature is above freezing.

Frost can occur even when air temperatures are close to 40°F due to a phenomenon called radiational cooling.

At night, especially under clear skies and calm conditions, heat from the ground radiates back into the atmosphere, cooling the surface more quickly than the surrounding air. This can cause temperatures at ground level to drop below 32°, even if the air temperature a few feet above the ground is warmer.