Watermelon plants are a labor-intensive plant to grow in a garden; however, many gardeners consider this work to be a labor of love that is worth the bountiful harvest. Watermelon plants require large amounts of water and fertilizer in order to produce healthy watermelons. Gardeners who are short on garden space sometimes opt to grow watermelons on trellis systems. When you grow watermelons in this fashion, be sure to prune the watermelon plants for optimal harvest. Pruning watermelons that do not grow on trellis systems is optional.
Examine the watermelon plants when they are well established. Find the primary stem of each plant. This primary stem will have many lateral branches extending out from it on both sides.
Keep the primary stem of each watermelon plant intact. In addition, keep the top lateral branch extending off from each primary stem.
Cut away the lateral branches between the top lateral branch and the eighth leaf node lateral branch from the top. This will enable you to train the watermelon vine to the trellis using this bare part of the vine.
Allow all lateral branches below the eighth leaf node to grow without pruning.
Monitor the watermelon plants regularly and cut away any branches and fruit that appear unhealthy or diseased. Dispose of these removed parts immediately to prevent a spread of disease. Strive to maintain a balance of vines and fruit on the watermelon plants.