February 21, 2024


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Do your tomatoes just look wrong? Here are some common problems in the summer garden


Even the most seasoned gardeners experience problems with their vegetable gardens from time to time. As Master Gardeners, we get a lot of “what’s wrong with my…”  questions.

Today, I thought I’d focus on a few common abiotic problems that many home gardeners deal with. Abiotic disorders are nonliving agents that include environmental, physiological and other nonbiological factors.

Fruit Set Problems

Poor pollination

Poor pollination

Squash, melons and cucumbers belong to the family Curcurbitaceae and they have a flowering habit that is unique among vegetable crops. They are monoecious which means they have separate male and female flowers. In order for fruit set to occur, pollen needs to be transferred to the female flowers and this is primarily done by bees. If there are a lack of bees you will notice the fruit starting to grow and then turn brown and shrivel up before they are ripe. An alternative to bee pollination is hand pollination which can be done by using a paintbrush and transferring the pollen from male to female flowers.

Another cause of poor fruit set is weather. Tomatoes, peppers, beans, squash, and other summer crops can will exhibit little to no fruit set when daytime temperatures exceed 90 F and nighttime temperatures stay above 72 F for several days, causing tomato pollen to become nonviable and blossoms to dry out and drop without producing fruit. Blossom drop can also occur if there is no pollination or temperatures dip below 55 F at night. Flowers may also fail to develop into fruit when sunlight is inadequate or if too much nitrogen is applied to the plants.


Every now and then some home gardeners experience bitterness when they bite into a perfectly good looking cucumber that they have grown for fresh use or pickling. Bitterness is due to the formation of Cucurbitacin and is usually found in the leaves, stems, and roots of the plant, but it can move into the fruit when the plant is stressed. The productions of Curcurbitacin is stimulated or depressed under certain environmental conditions. Cool temperatures can enhance bitterness so avoid growing them in cool or shaded locations. To help prevent bitterness, provide uniform moisture and ample nutrients for better fruit sets. You can cut the stem end off and peel the skin and the cucumber should taste like a regular cucumber.

Blossom End Rot

Avoid blossom end rot by maintaining even moisture in the planting area.

Avoid blossom end rot by maintaining even moisture in the planting area.

Tomatoes, peppers, eggplant, cucumbers, melons and squash can all suffer from blossom end rot. The fruit will start off with small, light brown spots at the blossom end of immature fruit. The affected area gradually expands into a sunken, leathery, brown or black lesion as the fruit ripens. You may even get hard, brown areas that develop inside the fruit.

Blossom end rot is caused by a low level of calcium in the fruit and water balance in the plant. It is aggravated by high soil salt content or low soil moisture and is more common on sandier soils. To reduce rot, monitor soil moisture to make sure that the root zone neither dries out nor remains saturated. If possible, water deeply but infrequently. Adding eggshells to the soil will not help with blossom end rot.




Summer vegetable plants need at least 6 hours of sun but the actual fruit does not do well with direct sun exposure. Many crops will see sunscald or sunburn because plants sometimes do not have a lot of foliage, and the fruits tend to be exposed to the hot afternoon sun, especially when the plants are young. To help protect plants, you can provide some type of shade or screening to the plants during the hottest months of summer.

Misshaped fruit

Every once in awhile you end up with misshaped cucumber or squash. There are several things that can cause this.

  • Poor pollination: If your cucumbers are funny shaped, you might have a problem with pollination.

  • Temperature: Sometimes when the temperature gets too hot, it can actually kill the pollen. Bees may carry both live and dead pollen to the female flowers. The live pollen will pollinate a portion of the cucumbers, while the dead pollen does nothing.

  • Insufficient water: Your deformed cucumbers could be caused by moisture stress, especially during hot weather.

With the right know-how, you’ll be able to work through these obstacles and watch your garden grow towards a successful harvest.

If you find you are having trouble with your garden or have other gardening questions, you can contact the UC Master Gardeners at (209) 953-6112. More information can be found on our website: ucanr.edu/sjmg.

This article originally appeared on The Record: Misshapen tomatoes? Here are some common problems in the summer garden


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