Dr. Grow: Understanding the birds and bees of the garden

There are two common laments that I have heard from gardeners over the last two months (other than "Those @#%* Japanese beetles!").

The first: "My tomatoes, pole beans and squash/cucumbers/zucchini are blooming their hearts out, but they are not setting fruit. What is happening, and what can I do about it?"

To explain what is happening, you must first understand Plant Sex Education 101. Plant flowers contain the sex organs for plants. Some plants have flowers with both the male and female organs on the same flower, some have male and female flowers on the same plant, while some plants have only male or only female flowers.

The male structure (stamen) contains pollen. The pollen is transported from the stamen to the female structure (stigma) by wind, bees, hummingbirds, moths, etc., and the pollen sticks to the stigma. This process is called pollination.

Pollination by itself does not ensure fruit development. For fruit development, fertilization must occur. I told this to an elderly gentleman once, and his rebuttal was a loud "I fertilized them with 12-12-12." I grinned and told him not 12-12-12 but boy/girl fertilization. He had a funny expression for a few seconds and then said, "Oh. Now I get it."

The actual process of fertilization occurs when the pollen forms a tube that travels the length of the stigma to the ovule in the female portion of the flower. This tube formation requires fairly specific environmental conditions to be successful. Without this successful tube formation the male gamete cannot fertilize the female egg. If the weather is too hot, too cold, too dry or too wet, the tube does not form properly and fertilization does not occur.

Without fertilization, the flowers dry up and fall off. Nature has a way of getting around this problem. Plants will continually set new flowers until fruit development does occur. My dad told me one time he watched his soybeans flower seven different times before fertilization and bean set occurred.

If you want to help Mother Nature, spray the blooms twice a week with a product called Tomato and Pepper Set or Blossom Set until you see fruit development. These products are plant hormones that enhance the ability of pollen to form the tube and get fertilization.

The second lament: "My tomatoes are not ripening." This particular problem is again weather-related. Tomatoes produce ethylene, which enhances the ripening process. During periods of stressful weather, the amount of ethylene produced is reduced, and the ripening does not occur.

You can get around this problem by picking your tomatoes when they start to turn color. Then place them in a brown paper bag. Don't let the tomatoes touch each other. Staple the bag shut and place it in your kitchen on the counter. Wait from three to seven days and open up the bag and enjoy your ripe tomatoes. Keeping the tomatoes in the bag increases the ethylene concentration around the tomatoes and ripening occurs.

The unusual weather conditions we have had this growing season have certainly presented challenges to gardeners: blossom end rot on tomatoes, beans not germinating, blossoms not setting, fruit not ripening and Japanese beetles, among several other problems. Don't give up. Just remember tomorrow is another day, next year is another season, and there are some things you can do to make your garden successful.

Send your gardening and landscape questions to Paul Schnare at P.O. Box 699, Cape Girardeau, MO 63702-0699 or by e-mail to news@semissourian.com.