Blossom drop
Tomatoes, peppers and beans abort their flowers when conditions are wrong for pollination: days above about 29 °C (85 °F), nights above 22 °C (72 °F) or below 13 °C (55 °F), drought, or very humid air. The plant keeps flowering and sets fruit when the weather settles.
Pollination & fruiting
What it looks like
The flower falls whole, snapping off at a joint in its stalk.
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Yellow stalks The flower stalk turns yellow at the knuckle before it drops. -
Flowers on the ground A scatter of fallen flowers under the plant. -
Bare trusses Tomato trusses with stalks but no fruit. -
Healthy leaves The rest of the plant looks fine.
How to confirm it
Look at the thermometer and the soil.
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Heat
Several days above 29 °C (85 °F) with warm nights point to heat.
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Cold nights
Early in the season, nights under 13 °C (55 °F) cause it.
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Dry roots
Pots that have dried out even once can drop every open flower.
What to do
Fix what you can and wait for the next flush.
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Water steadily
Keep the soil evenly moist.
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Shade and ventilate
Shade greenhouses and open vents in heat.
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Tap the flowers
Gently shake tomato trusses on warm mornings to release pollen.
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Grow heat-set varieties
Where summers are hot, choose varieties bred to set fruit in heat.
Prevent it next time
- Plant out after nights stay above 10 °C (50 °F).
- Mulch and water regularly.
- Choose heat-tolerant varieties for hot summers.
What not to do
Do not spray flowers with setting hormones or feed heavily; the plant simply needs kinder weather.
In the growing guides
Where the guides mention it, with plant-specific advice.
Sources
- Blossom drop in tomato, Alabama Cooperative Extension System
- Expect poor fruit set in tomatoes this week, University of Maryland Extension