If your pepper plant leaves turning yellow  , it is a sign that your plants are not getting enough of the key nutrient that keeps them green. The discoloration, which is called chlorosis, is a result of a lack of nitrogen and other essential nutrients such as potassium, calcium, magnesium, phosphorus and sulfur. When this happens, your plants will not have the energy to produce enough chlorophyll to keep their leaves and fruit healthy.

While nitrogen deficiency is the most common cause of yellow pepper plant leaves, other deficiencies are also possible. A lack of micronutrients such as magnesium and calcium can also be a problem for your pepper plants. These deficiency symptoms usually look similar to a nitrogen deficiency, but the veins of your pepper plant will remain green. You can fix a nutrient deficiency by fertilizing your pepper plants regularly with a 5-5-5 formula that is high in nitrogen and provides the other important elements. You can also use Epsom salt to enrich the soil with magnesium and crushed eggshells to provide calcium.

Yellowing Pepper Plant Leaves: Causes and Cures for a Bountiful Harvest

Other causes of yellow leaves on pepper plants include diseases and pests, cold temperatures and water stress. If your pepper plants are wilting or turning yellow because of cold weather, try moving them to a warmer location. If the cold is expected to continue for a long period of time, you can cover your plants with a tarp or blanket to help them stay warm.