That's what I do.Maybe 2 feet apart 3 to a hill in a 20ft row into black plastic.I get all the melons I can possibly eat and then some.When they start to run,I put the runners where I want using bobby pins to keep them in place.Move the pins outward every few days until they start to climb all over each other and can't roll in the wind.Works every time.

When the melons start to grow and are golf ball size.....place them on overturned pots to get them up in the sun and out of the shade of the leaves.If you are talking about watermelons.....write the date on a plastic knife or spoon and push it into the ground next to the melon.Add 30-35 days and they should be ripe.

I Heard growing too close together can limit how big the fruits get. should I thin it out further apart? What are some telltale signs that I will not get a good harvest?

az:

You will get bigger fruit with wider spacing. But I can't tell how much room yours have because don't know how wide they can spread. Mine are spaced about 3ft by 12ft. If they are really thick you can run into plants that set no fruit. A plant without fruit is nothing but a weed robbing space from the other plants.

If you want really big fruit a spacing of 6ft by 12ft would be better.

Let me give a little more detail. Watermelon will yield about 1 lb per sq ft. So for a plant to produce one 25lb melon it will need about 25 sq ft. A 10 lb melon about 10 sq ft. Figuring an ave of two melons per plant you'd need 50 sq ft for the plant producing two 25lb melons and 20 sq ft for the plant producing two 10 lb melons.