yellow pepper leaves

Asked April 16, 2019, 1:28 PM EDT

My potted pepper transplants have some yellow leaves.They receive 14 hours of artificial light everyday. The light source is about 8 inches above the plants. I water them when the soil at the top of the pot is very dry. i have one plant per 4 inch pot. Any suggestions? I no longer provide mat heat. The room temperature is a steady 70 degrees. I also have a small fan directed at the plants.

Horry County South Carolina

3 Responses

Hello, a couple of questions. Are you fertilizing them regularly with a complete fertilizer? Also, is the soil completely dry or just the top of the soil dry when you water? You may want to check that the soil is not completely dry under the top layer- make sure there is water getting to roots each time you water.

The top of soil does have algae in some pots. I have about 40 pots of peppers growing. Only 3vare turning yellow. The fertilizer I am using is a soluble commercial vegetable fertilizer.

The soil is damp below the top surface.

If there is some algae in the pots then the amount of watering could be too heavy. Or perhaps the media retains too much water. Too much water could lead to some root damage, which could lead to some yellowing as you are observing.Is your potting media a commercially made blend, containing a mixture of peat or organic materials, plus perlite/vermiculite, and limestone?

The other thing is that they may not be getting enough light, depending on the light you are using. 14 hours is enough length but the intensity may not be adequate.

A few other things:
Are the symptomatic peppers all the same variety? And are they different from other varieties? If so they may have different nutrient requirements and be exhibiting symptoms as a result. Are the roots on those plants more vigorous and becoming root-bound, or extending below the pot? If so they could become damaged and lead to some yellowing and nutrient deficiency.

Does the fertilizer contain micronutrients, such as manganese, iron, zinc, copper, boron, or secondary macronutrients like magnesium or sulfur? Nitrogen deficiency usually presents as lower leaves turning yellow, and then that progresses upward. Sulfur deficiency would be a more general yellowing. Magnesium would be interveinal yellowing/chlorosis. Iron deficiency would be yellowing of new growth/leaves- manganese or iron deficiency can sometimes be related to root damage as well. Have you increased rates as plants grow? Are those plants getting just as much as other plants when you apply fertilizer, or might they need more (for example, if they are a hybrid variety vs. open-pollinated or if based on the set-up they are sometimes missed during fertilization)? From the photo it is difficult to see the exact pattern of yellowing so difficult to do more than speculate about the specific nutrient.

Have you observed any fungus gnats flying around? Sometimes these can damage roots and lead to discoloration.