Why Aren't My Tomatoes Ripening?

March 22, 2019

Are you growing tomatoes indoors, or growing them outdoors in a cool climate? Gardeners in cool climates often struggle to get tomatoes to ripen before temperatures get too cold.

PC: Leslie F. Halleck

Tomatoes grow well with daytime temperatures between 70°F and 90°F (21–32°C) and a drop night temperatures to between 55°F and 75°F (13–24°C). Night temperatures above 85°F (29°C) can cause heat delay, where plants don’t set fruit. Cooler temperatures will slow or stop ripening.

If you live in a warm climate, and planted fall tomatoes, you might also struggle to get them to ripen once night temperatures get too cool in fall.

If you're growing tomatoes in your outdoor garden, but just can't get them to ripen, you're going to need to warm it up! If you haven't figured out how to control the weather (slacker), then consider bringing the plants indoors, under grow lights, to provide warmer temperatures and fruit ripening.

New BOOK! Gardening Under Lights: The Complete Guide for Indoor Growers


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