Gardening with Allen: Help tomato plants set fruit
By Allen Wilson
Published: June 26, 2021, 6:02am
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Prepare a tomato strategy before planting to prevent premature fruits. (iStock)
My tomato plants have produced dozens of flowers, but very few fruits have set. I have even shaken the flowers to make sure they were pollinated. Can you tell me what is wrong?
Your shaking of the flowers will make sure the pollen is transferred to the flower pistols. However the ideal temperature for fruit set in tomatoes is 60 to 75 degrees night temperature and 60 to 90 degrees day temperature. Our high day temperatures this weekend will actually be too hot for fruit to set even though the night temperatures will likely be in the 60s. And when the day temperatures cool to the proper range, we will probably be back into the 50s at night.
I used to plant my tomatoes on the south side of a dark colored fence. My tomato vines were trained right against the fence. The fence got warm in the direct sun and retained heat into the evening, so I got very good fruit set.
My tomatoes now grow next to a metal fence with cages for support. When temperatures are in their normal range, I pull a wide sheet of clear plastic around my plants in middle to late afternoon depending on day temperature. This traps heat around the plants which lasts into the evening.
Another way to improve fruit set is to trick the flowers into thinking they have been successfully pollinated. If sprayed with a hormone available in a product called “tomato blossom set” tomato flowers often set without pollination. The artificial hormone produces the same effect as pollination. The resulting fruits produce few if any seeds unless they become partially pollinated. They are also sometimes misshapen. However the flavor is not changed.
The two most common brands of tomato blossom set spray are Bonide and Monterey. They are available online and at most garden stores and sometimes also at hardware stores. Since tomato flowers hang down it is important to direct the spray upward into the flowers. Apparently the hormone is also absorbed by the leaves because directions on the bottle recommend spraying leaves around the flowers. Spray the flowers every two or three days to make sure the timing is right.
The spray is also apparently effective on other vegetables as the directions also indicate use on peppers, beans, cucumbers, eggplant, melons and okra. The spray may irritate the skin and eyes, wear gloves and avoid eye contact.
A common mistake is to thin or remove some of the tomato plant’s side shoots. This should only be practiced if you are trying to train plants to one or two vines around a stake or cord. Any time you remove leaves from a plant you are reducing its capacity to produce the energy which goes into fruit development.
