Watermelons are one of the easiest fruits to grow in the summer. Their biggest requirements are water and space. If you can provide these two elements, you should be able to grow watermelon. If you are limited in the amount of space you can provide for your watermelon, you can prune the tender branches to keep the plant within the confines of the allotted space.
Choose a watermelon vine that is growing past the borders you have established for the plant. Make sure the vine has at least one set fruit. Using your pruning shears, clip the branch just past a leaf.
Lift branches that are getting too long but do not have any set fruit, and then lay those branches back over an existing branch. This trains the branches to grow back into the growing area. When you see that a fruit has set, you can prune the branch back.
Identify the lead branch, which is usually the first branch to grow from the seed. There should be laterals that sprout from the sides of this main branch.
Prune off any laterals that sprout after the first one is allowed to grow. This will allow the plant to grow two long branches. This technique works especially well in long narrow spaces.