I have six tomato plants in my greenhouse. All are growing well and have small fruits forming but four of them have very curly leaves. They have all been fed and watered the same way. Can any one offer an explanation for the curly leaves?
Are they all the same varietal? Some tomatos have highly variegated, darker green leaves that look curled.
If that's not the case and if they look healthy and do not have the tell-tale signs of bug infestation (such as webbing or holes) I'd not worry about it...
I believe that this is caused by fluctuations in temperature. It happens when the greenhouse gets very hot during the day and then fairly cool at night. It does not appear to do the plants any harm and they go on to crop well.