How to Grow Watermelons Vertically

Mark a straight line over the selected planting site with powdered chalk. Pound a steel T-post into the ground every 4 to 5 feet over the line. Hammer the post into the ground until its flanged end falls under soil level. Alternatively, set each post in a bucket of concrete and sink it in the ground to prevent the trellis from tipping over.

Extend parallel lengths of high-tensile galvanized wire from one T-post to the other. Keep the lower wire 12 inches above the ground, and space the remaining wires at 6- to 12-inch intervals until you reach the tops of the posts. Wind each wire around the post several times and twist it with pliers before extending to the adjacent post.

Form a mound or small hill between every two posts. Tamp the top of the hill to level it and plant three seeds 1-inch deep on the top.

Provide each watermelon plant 1 to 1 1/2 inches of water every week using a soaker hose. Spread 3 lbs. of calcium nitrate per 100 feet or row to provide growing plants essential nutrients.

Train the vines of the watermelon plants to climb the wires of the posts. Secure the growing tendrils of the plants to the lowest wire using elastic ties, and then to the wires above as they continue to grow.

Create a pouch or sling for each tiny watermelon fruit when it grows the size of an orange. Using sharp scissors, cut an old T-shirt or stretchy fabric into 6- to 8-inch-wide strips for small varieties, or 12- to 15-inch-wide strips for larger varieties. Keep each strip of fabric long enough to tie it to the trellis easily. The sling supports the weighty fruit and keeps it from falling off the vines.

Place each pouch or sling under the melon, joining the ends together so it resembles a hammock. Tie the ends of the sling to the trellis to support the growing fruit.