When temperatures soar, it's common for tomato plants to slow down or even stop producing fruit.
While the plants may look healthy and continue growing, extreme heat can interfere with flowering, pollination, and fruit development.
If your tomatoes, for example, are flowering but not producing during a heat wave, the weather is likely the primary cause. Keep plants healthy with consistent care, and they should begin setting fruit again when temperatures return to a more favorable range.
When daytime temperatures remain above 90–95°F for days, many plants begin conserving energy by:
Heat Reduces Pollination
Tomatoes, for example, produce the best fruit when daytime temperatures are between 70–85°F and nighttime temperatures are 55–70°F. Most flowering plants bloom best when daytime temperatures stay between 65°F and 85°F. Prolonged heat above 90–95°F can reduce flower production, cause buds to drop, or shorten bloom time. When daytime highs consistently exceed 90–95°F or nighttime temperatures stay above 75°F, pollen can become less viable, and flowers may fail to set fruit or may simply drop from the plant.
Roots generally prefer cooler soil than the surrounding air. Mulch helps keep soil temperatures stable and reduces moisture loss during hot weather.
Flowers Drop Off
If you notice blossoms falling without forming tomatoes, heat stress is often the culprit. The plant is conserving energy until conditions improve.
Inconsistent Watering
Hot weather increases water demand. Allowing the soil to dry out and then soaking it can stress plants and contribute to blossom drop or problems like blossom-end rot. Keep the soil evenly moist by watering deeply.
Too Much Nitrogen
If plants have lots of lush, green foliage but very few flowers or fruit, they may be receiving too much nitrogen. Once tomatoes begin flowering, switch to a fertilizer formulated for fruiting plants that is lower in nitrogen and higher in phosphorus and potassium.
How to Help Tomatoes Through the Heat
Be Patient
The good news is that tomatoes often resume setting fruit once temperatures moderate. In many climates, gardeners see another flush of blossoms and fruit production in late summer as days become slightly cooler and nights begin to cool down.
Colorado Tip
At Colorado's high elevations, intense sunshine and low humidity can make heat stress even more pronounced. Consistent deep watering, mulch, and afternoon shade during prolonged heat waves can make a significant difference in maintaining healthy, productive plants.
If your tomatoes, for example, are flowering but not producing during a heat wave, the weather is likely the primary cause. Keep plants healthy with consistent care, and they should begin setting fruit again when temperatures return to a more favorable range.
When daytime temperatures remain above 90–95°F for days, many plants begin conserving energy by:
- Slowing growth
- Wilting during the afternoon
- Dropping flowers or developing fewer blooms
- Producing smaller fruits
- Ripening more slowly
Heat Reduces Pollination
Tomatoes, for example, produce the best fruit when daytime temperatures are between 70–85°F and nighttime temperatures are 55–70°F. Most flowering plants bloom best when daytime temperatures stay between 65°F and 85°F. Prolonged heat above 90–95°F can reduce flower production, cause buds to drop, or shorten bloom time. When daytime highs consistently exceed 90–95°F or nighttime temperatures stay above 75°F, pollen can become less viable, and flowers may fail to set fruit or may simply drop from the plant.
Roots generally prefer cooler soil than the surrounding air. Mulch helps keep soil temperatures stable and reduces moisture loss during hot weather.
Flowers Drop Off
If you notice blossoms falling without forming tomatoes, heat stress is often the culprit. The plant is conserving energy until conditions improve.
Inconsistent Watering
Hot weather increases water demand. Allowing the soil to dry out and then soaking it can stress plants and contribute to blossom drop or problems like blossom-end rot. Keep the soil evenly moist by watering deeply.
Too Much Nitrogen
If plants have lots of lush, green foliage but very few flowers or fruit, they may be receiving too much nitrogen. Once tomatoes begin flowering, switch to a fertilizer formulated for fruiting plants that is lower in nitrogen and higher in phosphorus and potassium.
How to Help Tomatoes Through the Heat
- Water deeply 2–3 times a week, or more often in very hot weather, depending on your soil. The key is "deeply".
- Mulch with 2–3 inches of straw, shredded leaves, or compost to keep roots cool and conserve moisture.
- Water early in the morning to reduce evaporation.
- Avoid heavy pruning during a heat wave, as leaves help shade developing fruit.
- If temperatures are expected to stay above 95°F for several days, consider using 30–40% shade cloth during the hottest part of the afternoon.
Be Patient
The good news is that tomatoes often resume setting fruit once temperatures moderate. In many climates, gardeners see another flush of blossoms and fruit production in late summer as days become slightly cooler and nights begin to cool down.
Colorado Tip
At Colorado's high elevations, intense sunshine and low humidity can make heat stress even more pronounced. Consistent deep watering, mulch, and afternoon shade during prolonged heat waves can make a significant difference in maintaining healthy, productive plants.