Heat Tolerance for Indoor Crops

Different plants have different heat tolerances, so you may find that your tomato transplants can tolerate hotter temperatures while your lettuce plants scorch. If you notice browning, scorching, curling, or crispy leaves close to the lamp, increase the distance between the lamp and the plant.

This tomato has grown about 12 inches too close to the hot 400-watt HPS lamp, and its leaves are beginning to curl because of excess heat. I must raise the lamp to create more distance from the plant.

Gardening Under Lights Book