A tomato flower that isn't pollinated, or can't develop, turns yellow at the joint behind it and drops off. Losing a few flowers is normal. Losing most of them means something in the plant's conditions is wrong.
Causes and Fixes
| Cause | Why it drops flowers | Fix |
|---|---|---|
| No pollination | Indoors there is no wind or bees to shake the pollen loose | Vibrate the flowers every day or two. See hand-pollinating indoor tomatoes. |
| Too hot | Daytime heat above about 85 to 90°F, or warm nights above about 75°F, damages pollen | Shade, ventilate, or raise the grow light |
| Too cold | Nights below about 55°F stop pollen from working | Move the plant somewhere warmer at night |
| Too little light | The plant can't support fruit, so it sheds flowers | More hours or a stronger light. See grow lights for indoor tomatoes. |
| Too much nitrogen | The plant grows leaves instead of fruit | Switch to a bloom nutrient at first flowers. See Kratky tomato nutrients. |
| Water stress | A container that runs low, or roots that are struggling | Steady top-ups. See topping up a Kratky tomato reservoir. |
Where to Start
Indoors, start with pollination: it is the most common cause and the easiest to fix. Outdoors in summer, start with temperature, because a run of very hot days or warm nights is enough to stop fruit setting until the weather cools. Flowers that form after conditions improve usually set fruit normally.
Back to Kratky tomato problems.
Frequently Asked Questions
Why are my tomato flowers falling off?
Most often because they weren't pollinated (common indoors) or because temperatures were too hot or too cold for the pollen to work.
Will tomato plants recover from blossom drop?
Yes. Once the cause is fixed, new flowers set fruit normally. The flowers already lost don't come back.
How hot is too hot for tomato flowers?
Daytime temperatures above about 85 to 90°F, or nights above about 75°F, can stop pollen from working and cause flowers to drop.