Peppers are sensitive summertime plants and grow only during the frost-free season. Peppers grow best at 70 to 80 degrees Fahrenheit and fail in frost and temperatures under 55 degrees. Cold temperatures lead to yellowing, wilting and turning leaves.
Pepper foliage depends on generous and consistent watering for color and health. Water pepper plants with 1 to 2 inches of water every week to keep foliage moist, lush and healthy. Use organic mulch to maintain soil quality between waterings. Thirsty pepper plants experience leaf wilting, drying, twisting and eventually death.
Pepper plants also require soil nutrition to maintain full, healthy foliage. Give pepper plants organic compost amendments to nourish soil and hold moisture. Feed the plants with organic or balanced fertilizer for healthy growth. Nitrogen-heavy fertilizers specifically encourage new, healthy vegetative growth, and may help turned leaves recover.
Peppers do best with bright, full sun and good air circulation and lose foliage in shade and crowded conditions. Lack of light leads to wilted, yellowed and shriveled foliage, while crowded conditions lead to leaf rotting and disease. Plant peppers in full sunshine with at least 18 to 24 inches of space for healthy growing.