Several leaves on my tomato plant have curled up. Why?

Question:

Several leaves on my tomato plant have curled up. Why?

Answer:

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.