Cherry Tomato Cultivation: What Causes Flower Drop? (Agriculture)

Hello. I am Takahiro Ogawa, an agricultural management supporter. While I thoroughly manage my own tomato farm and the farms I consult for, I tend to cut corners in my own home garden. Since I cannot spend much time or money on it, diseases and physiological disorders often occur. This year, the flowers on the cherry tomatoes I am growing at home have fallen off.
So today, I would like to talk about why flowers fall off during cherry tomato cultivation.

<Why do cherry tomato flowers fall off?>
There are various reasons why cherry tomato flowers fall off, but I would like to highlight the main ones.

・Too much base fertilizer at planting
Cherry tomato flowers fall off if there is too much nitrogen (N) due to over-fertilization.
When growing plants, we add base fertilizer to the soil at the beginning. In this case, there are many instances where people give too much fertilizer because they really want the plants to grow big and strong. If there is too much nitrogen, the energy does not circulate well to bloom flowers and produce fruit, but instead goes to the stems and leaves, so even if flowers bloom, they fall off before becoming fruit.
Not limited to cherry tomatoes, if a tomato plant does not bloom properly and produce fruit at the first flower cluster, it enters a state called "vine-blight" (tsuru-boke), where flowers bloom but then fall off.

If your cherry tomato flowers start to fall off, please check if you have given too much fertilizer.
If you feel you have given too much, it is a good idea to water the soil thoroughly. The nitrogen in the soil will wash away with the water, which may stop the flowers from falling.

・Lack of fertilizer
Cherry tomatoes produce many fruits as they grow, so they require a lot of nutrients.

You should not over-fertilize, but growing them without any fertilizer at all will also cause flowers to fall due to a lack of nutrients.
Try to apply additional fertilizer around the time the 3rd to 4th flower clusters bloom, which is when the nutrients from the base fertilizer typically run out. (This depends on the variety.)
By applying additional fertilizer appropriately, your cherry tomatoes can grow steadily without running out of nutrients.

・Excessive dryness due to lack of water
Cherry tomato flowers can also fall off if you neglect watering. If the soil or roots are dry due to a lack of water, the cherry tomatoes will become parched and eventually wither.
Since the cultivation period for cherry tomatoes is generally during hot weather, be sure to water them thoroughly and appropriately. If you are a professional farmer, solar radiation-proportional irrigation is ideal, but if you are gardening at home, please water them twice a day, in the morning and afternoon.

・Insufficient sunlight
Cherry tomatoes grown in environments with poor sunlight are prone to flower drop.
This is because the lack of sunlight leads to poor development of the cherry tomatoes. It means they are unable to photosynthesize and are not producing the glucose necessary for growth.

Cherry tomatoes that can no longer grow due to poor development will try to maintain their life by dropping their own flowers and leaves. By doing this, they prevent nutrients from spreading throughout the entire plant, attempting to concentrate the nutrients in the few remaining leaves and fruits.

・Failure to pollinate
Flowers produce fruit when the stamen and pistil are pollinated. Flowers that are successfully pollinated will have a cherry tomato fruit formed at the base, but flowers that are not pollinated will simply fall off.

Cherry tomato flowers are basically capable of natural pollination. In facility cultivation, bumblebees are used to ensure pollination, but in open-field cultivation or home gardening, they are pollinated naturally by insects and wind.

Flowers that are not pollinated for some reason will fall off, so if you want to ensure pollination, it is a good idea to pollinate them artificially.

・Extreme heat or cold
The ideal temperature for growing cherry tomatoes is said to be 20–30°C. Growing them in an environment that deviates significantly from this temperature will cause poor growth and lead to flower drop. In particular, with the recent extreme heat, pollen fertility drops, making it easier for pollination failure to occur, which causes flowers to fall. Be careful with greenhouse cultivation in midsummer.

Conversely, if the planting time is too early or if the temperature does not rise due to a cool summer, and you cannot grow them at the appropriate temperature, they will not be able to grow and the flowers will fall off.
When growing plants, you need to be especially careful about the temperature. Please try to create an environment that matches the ideal cultivation temperature.

This time, I talked about flower drop in cherry tomatoes.

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