Shirley Campbell

Master Gardener

Q: My plants are not looking good in all the heat. Would it help them to add some fertilizer when I water?

A: No, now is the worst time to add fertilizer to any plant showing stress from the heat and lack of water.

All plants are struggling for survival in this extremely dry and hot summer.

When survival mode kicks in, most plants stop growing, flowering and producing fruit.

It is not just the daytime heat that is harmful, but the nighttime highs are particularly damaging to plants.

Energy is made in the leaves from the sun during the day, but not at night. Plants consume energy both day and night and the amount used is related to the temperature  – the higher the temperature, the more energy used. Usually there is enough cooling at night to allow conservation of the energy produced during the day. However, with high nighttime temperatures energy use may outrun daytime production.

If one adds fertilizers to a stressed plant, it forces the plant to produce new growth and this requires a lot of extra energy.

This can be the “straw that breaks the camel’s back” for a struggling plant. Wait until the plants and soil have cooled and water is available before fertilizing. Most plants do well with fall fertilization if they need it.

Q: There are no tomatoes on my vines and the cherry tomatoes that are producing have tough skins. What am I doing wrong?

A: Tomatoes do not set fruit well when the overnight low temperature is above 70 degrees Farenheit, or when the daytime temperature is consistently above about 92 degrees Farenheit.

When these conditions occur, flowers will drop or fruit will be misshapen. Hormone-type “blossom-set” sprays have very little effect on the set of tomatoes during hot weather. Avoid excessive nitrogen fertilization.

Dry or very hot summers tend to produce thick skinned tomatoes. Even if you are watering regularly, when the air temperature is hotter, it can result in thicker skins as the plants try to conserve moisture. Inconsistent moisture levels in the soil can also contribute to the problem of tough skins. Tomatoes require two inches of water per week in July, August and September or apply enough water to penetrate to a depth of 12 to 18 inches. Use mulch to keep the soil moisture even.  

Q:  How can I prolong the shelf life of a tomato?

(This advice courtesy of Cook’s, America’s Test Kitchen)

A:  We’ve heard that storing a tomato with its stem end facing down can prolong shelf life.

To test this theory, we placed one batch of tomatoes stem-end up and another stem-end down and stored them at room temperature.

A week later, nearly all the stem-down tomatoes remained in perfect condition, while the stem-up tomatoes had shriveled and started to mold.

Why the difference?

We surmised that the scar left on the tomato skin where the stem once grew provides both an escape for moisture and an entry point for mold and bacteria. Placing a tomato stem-end down blocks air from entering and moisture from exiting the scar. To confirm this theory, we ran another test, this time comparing tomatoes stored stem-end down with another batch stored stem-end up, but with a piece of tape sealing off their scars. The taped, stem-end-up tomatoes survived just as well as the stem-end-down batch.

Shirley Campbell is an Ellis County Master Gardener, a Texas Rainwater Harvesting Specialist and guest columnist in the Daily Light. For further information, contact the Ellis County Master Gardeners at the Texas AgriLife Extension Service, 701 South Interstate 35E, Suite 3, Waxahachie, or call 972-825-5175 or e-mail: ellis-tx@tamu.edu.