How to Grow Melons on a Trellis

Honeydew melons, muskmelons and cantaloupes, which are Cucumis melo cultivars, and watermelons (Citrullus lanatus) all benefit from growing on a trellis. These annual vines are vulnerable to leaf diseases, but air moves freely through them when they're growing on a trellis, reducing infection-spreading wetness and humidity. A south-facing trellis also exposes melons to high levels of sunlight, boosting growth and fruit sugars. Grow ice-box watermelons with an average weight of about 10 pounds, such as "Blacktail Mountain."

A trellis for growing melons must be sturdy enough to support mature plants and fruits and be sited in favorable growing conditions. Build a trellis for melons on a full-sun, sheltered site with organically rich, well-drained soil, and position the trellis so that it runs east to west, and the growing area faces south. Hammer 6-foot posts 1 foot deep and 4 feet 8 inches apart to support a trellis panel 5 feet square. Drill pilot holes and screw the trellis to the panel. A trellis for growing watermelons should be especially sturdy. Hammer 6-foot steel T-posts 2 feet into the soil, and attach 5-inch square stiff wire trellis, or livestock panel, to the posts with stiff wire pieces and pliers.

Water and fertilizer requirements for melons growing on a trellis change over the growing season. Water young melon plants regularly so that the soil remains constantly moist. Don't overwater so that the soil becomes saturated because this can kill plants. Reduce watering for honeydew melons, cantaloupes and similar melons when the fruits are the size of a tennis ball, applying water only when the soil is dry to a depth of 2 inches, or when leaves begin to wilt. Fertilize melons with a 24-8-16 fertilizer diluted at a rate of 1 tablespoon per gallon of water weekly until the first flowers open, applying 1 gallon per 10 square feet. Apply an 18-18-21 product, diluted and applied at the same rate, until six weeks before the expected first frost date, or apply both products according to the manufacturer's instructions.

Melons growing on a trellis must have secure, flexible supports that expand as the fruits swell. Tie melon stems to the trellis as they grow, securing them with loose plant ties, twine or similar soft material once per foot, or gently thread the stems through the trellis holes. When melons and watermelons are heavy enough to begin to drag on the vine, tie the supporting material to the trellis and place the fruit inside. Onion netting, pantyhose, muslin slings, bird netting and old T-shirts are suitable for supporting melon fruits, providing the material is large enough to hold a mature fruit securely. The weight of the melon should rest on the material and not on the stem. Place melons growing at the base of the vine on tiles or bricks to lift them off the ground.

Growing melons on a trellis reduces the risks of pests and diseases, but plants should still be checked regularly. Melons are vulnerable to diseases such as powdery mildew, bacterial and fusarium wilt, fungal leaf spots, and cucumber mosaic virus. Examine melon leaves for white, powdery patches, unexplained wilting and discolored patches or patterning. Avoid wetting foliage when watering, remove all weeds and remove severely affected plants. Melon pests include aphids, which cluster on shoot tips and the undersides of leaves, squash vine borers and squash bugs. Blast aphids off foliage with a jet of water from a garden hose, and pick off leaves infested with squash bugs eggs, which are copper, and adults, which are light green maturing to dark gray. Squash vine borers cause unexplained wilting. Check for holes in wilted stems and prune affected stems below the holes with pruning shears. Sterilize the blades by wiping them with rubbing alcohol between each cut.

Melons are ready for harvest in late summer. Cantaloupes, honeydews and similar melons begin to ripen three to four weeks after they stop growing. Cantaloupes change color from gray-green to yellow-buff and the netting on their rinds stands out when they're fully ripe. A crack also appears encircling the bases of the melon stems, and the fruit develops a musky odor. Ripe honeydews turn cream-colored and the blossom end gives slightly when pressed. Don't repeatedly test honeydews for ripeness, however, because this damages the blossom end so that it feels soft even when the fruit isn't ripe. Harvest watermelons when their undersides turn from greenish-white to buttery yellow.