Tomato Pollination

tomato seedlings in Styrofoam cups

tomato seedlings in Styrofoam cups

Q: I have a beautiful tomato plant growing in a container on my patio. It faces west and gets plenty of sun. I feed it according to the instructions on the fertilizer box, and while the plant itself is beautiful and I get many blossoms, the blossoms bloom and eventually just drop off the stem. I am sure I am doing something wrong but don’t know what. I love home-grown tomatoes, and since I don’t have a garden anymore, I have to settle for patio plants. Could you please give me some advice?
– Peg Nolan
A: The absence of fruit you have experienced is most likely the result of insufficient air movement – as in a wind or a breeze – around your tomato blossoms. It is also an indication that bees probably do not visit your patio-grown tomato plant. Tomato plants are both self-fruitful and autogamous.
A self-fruitful plant pollinates itself, so that even if you have only one tomato plant, you should still get fruit. However, tomato plants are also autogamous, which means that pollination of each flower is by its own pollen and that cross-pollination between flowers, while it may occur, is not needed for fruit production.
The advice typically given when a tomato plant flowers without giving fruit is to gently shake the flower stems. Normally, the vibration created by an average garden breeze is enough to move the pollen from stamen (male flower part) to stigma (female part).
However, if your patio is enclosed on three sides, for example, there may not be enough air movement to agitate your tomato flowers sufficiently for pollination to occur.
Autogamy or self-pollination in tomatoes can also take place with the assistance of bees, but not in the usual way. Typically, bees pollinate flowers by foraging for nectar. Nectar-containing nectaries are found at the bottom ends of flower petals, and in order to reach them, the bee’s body must rub against pollen, which is found on the top ends of filaments that rise above the petals. Pollen grains stick to the bristles on the bee’s body and are then deposited on the female stigma, located in the center of the filaments, as the bee continues to forage for pollen either on the same flower or another.
In the case of tomato flowers, which are poor sources of nectar, bees affect self-pollination not by carrying pollen grains on their bodies between male and female flower parts but simply by the vibrations they create when buzzing around the flowers. When a bee buzzes next to a tomato flower, the vibration shakes the male pollen grains onto the female stigmas. In greenhouses where tomatoes are grown, bumblebees are much better pollinators than honeybees since the former’s buzz is significantly stronger than the latter’s. In greenhouse tomato production, where bumblebees are not available, pollination is achieved by the use of fans.
Although you say you have fertilized according to “instructions on the fertilizer box,” you might want to cease all fertilization until fruit has formed. Aside from fertilization at planting time, many backyard tomato growers will not fertilize again until tomatoes have actually begun to appear on the plant or until the first tomatoes have been harvested. Based on my own experience, I would say that in the case of most vegetables, including tomatoes, post-planting fertilization may not be needed at all if soil preparation and pre-planting fertilization have been adequate.
Because of our long growing season, tomatoes may be planted through August, with late crops still being harvested, during mild winters, into December.
In recent years, heirloom tomatoes have caught the fancy of increasing numbers of gardeners. Heirloom varieties are at least 50 years old, have been passed down through families or ethnic groups and come true from seed. In other words, if you save seeds from an heirloom variety, they will produce plants with the same type of tomato when planted the following spring – unlike hybrids, which do not come true from seed.
Heirloom tomatoes have several advantages over hybrids. Heirlooms have outstanding flavor, come in a variety of colors (pink, yellow, orange, maroon, purple), may be marbled or striped, have unusual shapes (until the 20th century, tomato varieties were every shape but round) and an extended growing season. However, heirlooms are more prone to disease than hybrid varieties.
TIP OF THE WEEK: To save tomato seeds, remove seeds with pulp from a ripe tomato and put in a bowl with a little water. After four days, separate seeds from pulp and dry on paper towels for six days. When dry, place seeds in airtight containers. Store them indoors in a dark, cool, dry location and they should maintain their viability for three to five years.

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