Details: I have 5 big ( by my standards) girls in my garden. They are about 6-7 ft tall and 5-6 ft wide. They are in the ground (sand). There is a 3' wide depression around each plant that I fill with water twice a day. About 2-3 gal ea time. They wilt if I miss a watering. Question: Do the roots of a plant this size growing out more than 3ft from the plant.? Should I be watering the area further away from the plant. Say, 6 ft out from the stem? I don't mind watering more but don't want to waste it. Oh, I'm using filtered house water at ph 7.5 Any help please.