The Reasons Why Your Tomato Plant Has Flowers But Doesn't Form Tomatoes
Yellow flowers on tomato plants signal the countdown to ripe, juicy tomatoes. So what if it’s been weeks, the flowers are falling off, and you still don’t see fruit forming? It could be due to a simple cause. We’ll cover the natural development of tomatoes and explain why tomato flowers may be falling off without forming tomatoes.
When I see those first yellow flowers on my tomatoes, I can almost taste the harvest. So when they start dropping off without forming fruit, it can be alarming.
It’s not hard to determine the cause of tomato flower drop, and the fix is usually fairly simple.
Why Your Tomato Flowers But No Fruit Sets
How Tomato Flowers Develop Tomatoes
First, it helps to understand how tomatoes develop from the flower.
Tomato flowers are self-pollinating. Once the flower opens, it will stay open for 1 to 3 days. During this time, the flower needs to release pollen so it can reach the ovules. This can happen with wind or buzzing insects. Within 2 to 5 days of successful pollination, there will be visible signs of fruit set. By 7 days, you should clearly see a small tomato.
After the flower has been pollinated, it will fall off. But the green calyx will remain. If you look closely – or take a picture and zoom in – you will see that tiny green swelling. This means everything is progressing as it should.
Tomato flower drop is only concerning if the entire blossom, including the calyx, falls off. If it falls off at this point, then the cause is poor pollination.
Taking close-up pictures and zooming in lets me see the very tiny tomato starting to form.
Signs of successful pollination
- Yellow petals begin to wilt.
- Petals dry up and eventually fall off.
- The green calyx (the star-shaped leaves behind the flower) stays attached.
- The ovary—the small green bump behind the flower—begins to swell.
That swelling is called fruit set, and it's the first reliable indication that pollination and fertilization were successful.
Common Causes of Tomato Flower Drop
Temperatures
The most common cause of tomato flower drop is temperature extremes. This one can be easy to diagnose but harder to fix. You can’t control the weather. But you can use shade cloth when it gets too hot and use warming methods when the nights get too cold.
Too Hot for Tomato Flower Pollination
Even though tomatoes are a warm-weather crop, it can get too hot for them. When temperatures exceed 85ºF for an extended period of time with night temperatures staying above 72ºF, tomato flowers will fall off. Source: Alabama Extension
Using shade cloth can help cool the plants. But don’t use too thick of a cloth. Nothing that shades more than about 40%. Tomatoes still need sunshine to grow.
Too Cold
Flowers will also drop off when it’s too cold. Gardeners in cool climates often see this in late spring and early summer. If this happens, you can use frost blankets and milk jugs to protect from frost. Be patient. As the weather warms up, the plants will be able to set tomatoes.
Poor Pollination
Tomato flowers will drop off if they aren’t being pollinated. Since the flowers are self-pollinating, it doesn’t take much to shake the pollen loose inside the flowers. To help move the pollen inside the flowers, you can gently shake the plants for a few seconds. Usually the wind and buzzing insects will do this for you.
Signs pollination failed
Instead of swelling:
the entire blossom yellows
the flower stem develops an abscission layer (weak band)
the whole flower drops off
This is called blossom drop and usually means the flower never set fruit because temperatures, humidity, or plant stress prevented successful pollination or fertilization.
Excessive nitrogen
Tomatoes benefit from a targeted fertilizer schedule. Once the tomato plant starts flowering, you need to cut back on nitrogen. Increase the amount of phosphorus with a 10-20-10 or 5-10-10 formulation.
What if your tomato plant doesn’t have any flowers? Or very few?
If you're not getting any flowers at all or very few, it could be for similar reasons.
- Not enough sunlight
- Too hot or too cold
- Not enough water
- Too much nitrogen
How to encourage tomato flower pollination
When you notice tomato flowers forming, it’s time to:
- Adjust your fertilizer
- Water consistently
- Shake your plants or watch for bees and wind that will help pollination
Tomato Flower FAQs
How long does it take to pollinate a tomato flower?
The actual transfer of pollen is almost instantaneous. Once a flower is open, pollen is released when it is vibrated by wind, insects, or by tapping the flower.
Tomato flowers remain receptive for approximately 1–3 days, during which pollination normally occurs. If pollination does not happen during this window, the flower is much more likely to abort and drop off.
How can you tell if a tomato flower has been pollinated?
There isn't a visible "pollination happened" signal immediately. Instead, you watch for the plant's response over the next several days.
How long after pollination does the tomato start forming?
The ovary begins growing almost immediately after fertilization. Although cell division starts very quickly, gardeners usually don't notice anything for 2–5 days. By 5–7 days, the tiny tomato is usually obvious as a pea- or BB-sized green fruit.
When my tomato plants start flowering, I check them almost daily to see if tomatoes are forming. During this pollination and fruit-set time, it’s crucial that there is wind or insects to help. You may have to get out and shake your plants and put up shade if it’s too hot. Always keep up consistent watering, and adjust your fertilizing schedule.
Once you know what to look for, it’s fun to watch all those flowers turn into tomatoes.
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