The Q&A Archives: heat stress

Question: This year my plants didn't do so well. I am just now getting hot peppers, only for about a few weeks I have had sweet peppers, and my tomatoes and asparagus beans actually stopped growing altogether for a month or more! Is there any way to combat heat stress? Maybe shade them or water them during the hottest part of the day? Will overhead watering cool them off or just boil them? Also, my jalapenos and habaneros have no heat unless you bite a seed!

Answer: There are many factors that can affect production. I hope the following will help you trouble shoot.

Tomatoes and peppers and beans are all full sun crops, so they need the good exposure to light. Some varieties however are more sensitive to temperature; some do well in cooler seasons but some can handle excessive heat better. So to some extent the specific varieties you grow will affect the outcome in an especially hot or cold season.

Heat in and of itself is not necessarily a problem, although most plants will slow down when temperatures exceed about 85 degrees. They should come back into rapid growth once the temperatures moderate.

Constant overhead watering will be an open invitation to foliage disease problems so it is not a solution. The better approach is to apply water to the root area as needed to keep the soil evenly moist, meaning consistently like a wrung out sponge.

Using a mulch will help keep the soil evenly moist as well. Adding organic matter during the soil preparation phase prior to planting also helps assure an evenly moist yet well drained soil.

Also maintain ongoing adequate fertility so that the plants are in optimum health, this allows them to withstand stress better. Tomatoes and peppers both require a relatively rich soil.

Avoid excessive pruning to your plants; the foliage shades the fruit and prevents sunscald.

Pay attention to both air and soil temperatures in the spring. Cold soil and cold air at planting time can both set plants back, sometimes stunting them for the whole season. This past spring was cold and damp, so the soil temperature would have stayed colder longer thus indicating delayed planting. Peppers and tomatoes both prefer warm soil, so planting should be delayed until the soil has had time to warm up.

Seedlings or transplants that were left too long in their containers and became rootbound would also potentially be stunted.

Flowers and young fruit may abort during a cold spell, and flowers may drop when nights are warm thus preventing fruit set. This can cause a delay in successful fruit set.

Picking ripe fruit will encourage additional production, leaving ripe fruit on the plant can slow it down.

With peppers, sweet peppers get sweeter as they turn riper and hot peppers get hotter as they ripen. With hot peppers, the specific variety and also seed strain can have a big influence on hotness, so you may want to experiment with different kinds. The heat is also in the ribs, so a well developed pepper should be hotter than a skimpy one.

All in all, many mid Atlantic region gardeners are complaining about the growing season this summer. Sometimes there is just not much we can do except hope for more favorable weather next year.

In the meantime, review your experience this season and see if there are steps you can take to improve your chances next year. Careful selection of varieties, soil testing to fine tune soil amendments, careful watering practices, and so on can all have a positive effect for example. I hope you have a better season next year.

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