I have a question about potatoes growing in containers. I planted the correct amount of seedlings (1 per 5 gallon in a 20 or 25 gallon container, I have both). They are growing like mad. But now the containers are full to the brim after hilling, and there is already 18" of new growth on top. Should I let the potatoes grow and stop hilling? Or should I try to enlarge the sides of the pots and keep hilling? T hanks.