Why are my tomato leaves curling?

I have the same problem & I thought it was because of the hot, dry heat here in Texas. After much research, I have read that it may be from whiteflies, causing a viral infection & require that the plants to be destroyed.

Another cause could be cool moist temperatures causing them to curl the opposite dry, hot temperatures & uneven watering causing the leaves to curl. Both of the last two suggestions are referred to as physiological or protectant measures in order for the leaves against too much or too little watering. i would think that you would need to assess your plants for the whiteflies & then look to your area for which yours might be. A good resource that I had found is the Gardening app.

usually for lack of watering. try this. Epsom Salts. 1 teaspoon in a gallon of water and use for a week. reload every week.

not necessary a lack of water.....https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-leaves-curling.htm

Tomatoes require a lot of water. I had one in a huge pot last year that when it was really hot would take up to three gallons of water to keep from willing. I watered morning, early afternoon and evening to keep up with what the plant wanted. It stayed healthy and produced way too many tomatoes for a patio tomato, it grew to be a five foot plant.