Though they take up considerable space and require a long growing season, many home gardeners can't resist planting a few watermelons and muskmelons.
Melons are relatively easy to grow. Their basic requirements are full sun and a fertile, well-drained soil. Heavy, poorly drained soils can often be improved by incorporating organic matter, such as compost or well-rotted manure, into the soil.
Watermelon and muskmelon are warm-season crops. Plant melons after the danger of frost is past and soil temperatures have warmed to 60 to 70 degrees Fahrenheit. Melons can be planted in mid-May in central Iowa. Gardeners in southern Iowa can plant about 1 week earlier. Plant 1 week later in northern areas of the state.
Muskmelon and watermelon are normally planted in hills. Plant 4 or 5 seeds per hill at a depth of 1 inch. Later, remove all but 2 or 3 healthy, well-spaced plants per hill when seedlings have 1 or 2 true leaves.
For an earlier crop, melon transplants can be started indoors. Start seeds indoors 3 to 4 weeks before the anticipated outdoor planting date. Plantable containers, such as peat pots, work best as both plant and container are transplanted directly into the garden, resulting in little damage to the transplant's root system. Sow 3 or 4 seeds per container, later remove all but 2 seedlings. Transplant outdoors when plants have 1 or 2 true leaves. Harden the plants outdoors for a few days prior to planting to lessen transplant stress. Initially place the transplants in a shady, protected location and then gradually expose them to longer periods of direct sun.
Hills of muskmelon should be spaced 3 to 5 feet apart with 5 to 7 feet between rows. Watermelon hills and rows should be spaced 6 to 8 feet apart. If garden space is limited, bush-type varieties of muskmelon and watermelon are available.
Home gardeners can promote early melon production by using black plastic mulch. Black plastic promotes spring growth by warming the soil. The plastic mulch also helps to conserve soil moisture and control weeds. Lay the black plastic over moist soil on a calm day. Anchor the edges of the plastic mulch by making furrows 2 or 3 inches deep, placing the edges in the furrows, then covering with soil. To plant, cut holes in the plastic with a sharp knife or bulb planter. The holes should be in the center of the plastic film and just large enough to plant the seeds or transplants.
Suggested muskmelon varieties for Iowa include 'Earlisweet' (early maturing, 2 to 3 lb. fruit), 'Eclipse' (round 6 to 8 lb. fruit), 'Athena' (oval 4 to 6 lb. fruit), 'Aphrodite' (oval 6 to 9 lb. fruit), 'Superstar' (oval 6 to 8 lb. fruit ), 'Ambrosia' (round 4 to 5 lb. fruit), 'Hale's Best' (oval 4 to 5 lb. fruit, heirloom), 'Earlidew' (honeydew type, pale green flesh), and 'Passport' (hybrid melon, green flesh).
Excellent watermelon varieties include 'Crimson Sweet' (red-fleshed, seeded, blocky round fruit, 20 to 30 lb.), 'Royal Sweet' (red-fleshed, seeded, blocky oval fruit, 20 to 25 lb.), 'Sangria' (red-fleshed, seeded, blocky oval fruit, 20 to 26 lb.), 'Crunchy Red' (red-fleshed, seedless, round to oval fruit, 15 to 18 lb.), 'Gypsy' (red-fleshed, seedless, round fruit, 13 to 17 lb.), 'Millionaire' (red-fleshed, seedless, oblong fruit, 13 to 20 lb.), 'Sweet Beauty' (red-fleshed, seeded, oblong icebox-size fruit, 5 to 7 lb.), 'Yellow Baby' (yellow-fleshed, seeded, round fruit, 9 to 12 lb.), and 'Amarillo' (yellow-fleshed, seedless, round fruit, 12 to 14 lb.).
A seeded variety (pollenizer) must be planted with seedless watermelon varieties for proper pollination. Pollinator seeds are often included in seedless watermelon seed packets.