One of the comments we hear frequently at our Master Gardener Demonstration Garden is “I’ve tried but I can’t grow peppers” or “My plants never produce any decent peppers”. We hear your frustration! While pepper plants are not hard to grow, it can be tricky getting them to set fruit. Peppers have some unique needs which must happen in specific time periods if you want a successful crop. Being a bit temperamental, peppers are the DIVAS of the vegetable world.
Let’s take a walk through the 3 most critical concerns for growing and harvesting peppers: soil temperature, too-high air temperature, and too much nitrogen.
Soil Temperature
Soil temperature is the most critical aspect for getting peppers to fruit. When peppers are planted in cold soil, they go to sleep (so to speak). As the soil warms, the pepper will revive and the plant will grow but the signal that tells the plant to set fruit may not activate properly, resulting in plant growth but little or no fruit set. Warm soil for peppers is a minimum of 65° F but they are happier at 70°F. In many areas the soil does not warm to that temperature until June.
ACTION: Put your pepper into 1-gallon pots and hold them until the soil temperature reaches 65°F minimum. The temperature should be taken early in the morning at a depth of 4–6 inches.
NOTE: When holding peppers for the soil to warm up, they may want to start flowering. It’s a good practice to pinch the flowers off so the available energy goes to developing strong roots and a vigorous plant.
High Air Temperature
Any time the temperature is under 85 degrees the peppers can bask in full sun, but be mindful of sun scald. When the daytime temperatures go over 85°F, pepper pollen becomes inactive. Even if the pollen is moved from flower to flower, no pollination will occur and there will be no fruit set. Many Contra Costa locations stay well over 85°F for days on end. We have found the best way to work with this issue is to provide the peppers with some shade.
ACTION: Use shade cloth over your pepper bed or containers to keep the temperature lower. Shade cloth is sold in percentages and 30% shade cloth will be adequate. 30% refers to the amount of light which is blocked. Shade cloth is available in two types, woven and knit. We prefer knit because it will unravel less when cut.
High Nitrogen
Pepper plants love nitrogen (the N of N-P-K on a product label) but the plant will use high nitrogen to grow a BIG bushy plant at the expense of setting fruit. Peppers need the nitrogen, but they need to be fed in a way that does not counteract fruit set.
ACTION: You will want to feed peppers with a low nitrogen product, feeding a little more often. An organic liquid product would be a good choice because it can be mixed at 1/4 to 1/2 strength. Organic fertilizer releases its nutrients slowly making it less likely the leaves will burn.
General guidelines for feeding peppers:
Wait a week after potting your peppers into 1-gallon pots then feed with a low nitrogen fertilizer. If peppers are going to be held 4–6 weeks before planting, feed once or twice using low nitrogen fertilizer.
When transplanting into the garden use a low nitrogen fertilizer. Add additional phosphorus; bone meal, rock phosphate and fish bone meal are all good sources for adding additional phosphorus. Follow the rate listed on the product you are using.
When the first flowers appear, apply a low nitrogen fertilizer and additional phosphorus to promote fruit development.
As the season progresses continue to fertilize with a low nitrogen product every 2–4 weeks. Peppers benefit from a 1/2 strength liquid organic foliar feeding every couple of weeks especially if the crop is heavy, keeping the nitrogen low. The easiest way to apply a foliar feed is with a one to two-gallon pressure pump sprayer. For a few plants a 1-quart handheld sprayer will do but for a large area, a 1–2 gallon sprayer will make the job much easier.
Note on staking peppers: Many pepper plants can get quite tall and have a heavy fruit set. It is a good practice to stake your peppers when you put them in the ground, so the roots are not disturbed later. If the peppers in the 1-gallon pots get tall they should be staked as well. Tie the peppers loosely to the stake so that the stem has some movement. This movement causes the peppers to form a strong stem.
We encourage anyone who has struggles with growing peppers in the past to take another run at it. Following these guidelines, we believe you will be pleased with the results.
For more information about growing peppers, see this website:
https://ipm.ucanr.edu/home-and-landscape/peppers/index.html
Photos courtesy of Bonnie Dwyer
Help Desk of the UC Master Gardeners of Contra Costa County (BHD)