It is important to have a constant uniform moisture supply to produce a high-quality crop and to have the spring crop mature before high summer temperatures. Mulching can help conserve water and reduce weeds. Entire plants can be cut when very young, half grown or full grown. Tender leaves can also be harvested from full-grown plants. Store all harvested collards in the refrigerator.
Aphids can also be a serious problem, especially during cool weather.
Common disease problems include black rot, downy mildew and Alternaria leaf spot. Black rot causes the most serious damage and appears as V-shaped lesions down the leaves and spreads into the water conducting system of the plant. Black rot is caused by a bacterium that is seed-borne or that can be transmitted by transplants. Warm, moist weather favors the disease. There is no control for black rot once it is established in a planting.