Several leaves on my tomato plant have curled up. Why?
The curling of the tomato leaves may be a physiological disorder referred to as leaf roll. Affected leaves roll upward and inward. The leaves may also become thickened, giving the foliage a leathery appearance.
Leaf roll often occurs after a heavy rain, plants have been severely pruned, or the plant’s roots have been damaged by deep cultivation. Leaf roll does not reduce crop yield or quality. Leaf roll is usually a temporary problem. Plants typically recover on their own.