Watermelons need a lot of space. They develop a deep and intricate root system that can stretch out nearly a foot and a half from the vines base and it seriously complicates any effort to move them. Learn How Long Does Watermelon Take To Grow What Month Do You Plant How To Guides Tips And Tricks Watermelon Plant Growing Watermelon From Seed Watermelon Seeds You can gently cut the bottom of the pot just before planting to allow easy access for the roots to stretch out. How deep do watermelon roots grow . Watermelon plants have moderately deep roots and watering is seldom necessary unless the weather turns dry for a prolonged period. Watermelon grows in all parts of the USDA planting zones when. I say about 12 inches. Sow watermelon seeds 12 to 1 inch deep into the soil. Watermelon roots commonly grow 8 to 10 or more inches deep. Space watermelons 6 to 12 feet 18-36 m apart. Space watermelons 6 to 12 feet 18-36 m apart. They can be up 6 feet deep they say. The tapro...