Tomatoes are vulnerable to a lot of diseases, it is particularly important that you rotate them; don't grow tomatoes in the same spot more than two years in a r

Tomatoes are vulnerable to a lot of diseases, it is particularly important that you rotate them; don't grow tomatoes in the same spot more than two years in a row, and wait at least two years before growing them there again. If growing them in pots sterilize the soil over the winter (there are several ways you can do this).