This is my first time growing watermelons, and I'm getting anxious that they won't ripen before the weather gets too cold. I have about eight melons of various sizes, but the largest of them is maybe 9" in diameter. They have been getting plenty of sun and water, and just seem to be growing painnnnnfullly sloooowww. Can anyone tell me if this is normal? I planted the seeds way back at the end of April!