Blossom drop
Open flowers dropping from the plant without setting fruit, leaving a bare stalk. In tomatoes, peppers and chillies it is almost always temperature: pollen is sterile above roughly 30 °C and below roughly 13 °C, so the flower opens, fails to pollinate and is shed. It is a fault in the conditions rather than in the plant.
Nothing available to a home grower will fix this
Nothing applied to the plant fixes blossom drop caused by temperature. The lever is the growing environment, and in an outdoor season that is largely the weather.
source
GrowingHQ editorial positionmoderate confidence
Recorded because it is a problem people buy products for, and the products do not address the cause.
- GrowingHQ editorial synthesis — GrowingHQ
Checked 2026-08-13
What brings it on
Night temperatures below about 13 °C or day temperatures above about 30 °C while the flowers are open, and very dry or very humid air, which both interfere with pollen release. Under glass in a heatwave it can take every flower on a truss.
source
Sourced guidancehigh confidence
- University of Minnesota Extension — University of Minnesota: Tomato — blossom drop
Checked 2026-08-13
Usually seen: May, June, July, August
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Ventilate and shade a greenhouse in hot weather, and delay planting out until nights are reliably warm. Keeping the plant evenly watered helps it cope with the temperature it does experience.
source
Sourced guidancehigh confidence
- University of Minnesota Extension — University of Minnesota: Tomato — blossom drop
Checked 2026-08-13
Dealing with it once it is there
- Improve the conditions and wait for the next truss. Flowers already shed will not set, and a plant that drops one truss in a heatwave usually sets the next one normally once temperatures fall.
source
Sourced guidancehigh confidence
- University of Minnesota Extension — University of Minnesota: Tomato — blossom drop
Checked 2026-08-13
- Tapping the flower trusses or lightly shaking the plant in the middle of the day helps pollen release where still air rather than temperature is the limit — most useful under glass.
source
Sourced guidancemoderate confidence
- Royal Horticultural Society: Tomato — pollination
Checked 2026-08-13
What it affects
Signs that lead here
Each of these lists the other things that produce the same sign, and how to tell them apart.
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.
Plant-specific guides
Where this is one of several causes that look alike on a particular plant, GrowingHQ publishes the differential rather than the general answer.