How to grow Watermelon

Where to plant

Watermelons grow best in sandy loam in full sun. On clay soils, raised rows mulched with black plastic film increase yields significantly by warming the soil. Give the vines plenty of space: they sprawl 6 feet or more.

Seeds rot in cold soil, so wait until all danger of frost is past and the soil has warmed above 65°F. The sweetest melons grow in long, hot summers; in short northern seasons, use transplants, black plastic and smaller, quicker varieties.

• Central Florida: sow or plant from January to March for early summer melons. North Florida and the Gulf South: March and April. South Florida: January to March and again in August and September.
• Texas: March and April. Desert Southwest: February and March, so melons ripen before the extreme heat.
• California: plant from spring into early summer; inland valleys give the sweetest melons.
• Mid-South, Mid-Atlantic and Southern Plains: plant from May into early July.
• Northeast, Midwest, Northern Plains, Mountain West and the Pacific Northwest: plant in late May or June with transplants and black plastic, choosing short-season varieties and your warmest spot.
• Hawaii: any month. Alaska: start indoors in April and plant out under cover after the last frost; choose short-season varieties.

Choosing a variety

• Crimson Sweet is a reliable, sweet, disease-tolerant standard; Sugar Baby is a compact icebox melon for small gardens and short seasons.
• Seedless watermelons must be planted alongside a standard seeded variety, as their own pollen is not fertile.
• Choose disease-tolerant varieties (fusarium wilt and anthracnose) in humid regions such as Florida.

How to plant

1. In short-season areas, start seed indoors in pots or cells only about 3 weeks before planting out, at 80°F to 85°F; large seedlings transplant poorly. Plant seedless seed one per pot.
2. Lay black plastic over the row before planting, especially on heavier soil or in the North.
3. Sow 2 to 3 seeds 1 inch deep in hills 6 feet apart, with 7 to 10 feet between rows, and thin to the strongest plant. Set single transplants 2 to 3 feet apart in the row.
4. Water in transplants with a starter fertilizer.
5. Cover young plants with row cover against cucumber beetles until they start to bloom, then remove it so bees can pollinate.

Watering and feeding

Watermelons have moderately deep roots; water deeply while vines grow and fruit swells, especially in dry spells and on sandy soil. Ease off as the melons approach ripeness, which helps flavor. Uneven watering can cause blossom-end rot and split fruit, and black plastic mulch helps keep moisture even.

Feed lightly at planting and when the vines start to run.

Pruning and care through the year

• Keep weeds down with shallow hoeing until the vines cover the ground.
• Male flowers appear first; female flowers, with a tiny melon at the base, need several bee visits for well-shaped fruit.
• Watermelons cross with other watermelons, but this only affects saved seed, and they do not cross with cantaloupe, squash, pumpkins or cucumbers.

Harvesting

Use several signs together: the curly tendril nearest the melon turns brown and dry; the surface loses its shine and turns dull; the rind resists a thumbnail and feels rough; and the ground spot underneath turns from white or pale green to creamy yellow. The ground spot is the most reliable sign. Thumping is unreliable.

Melons do not ripen further once picked, so wait for the signs. Cut the stem with pruners. Uncut melons keep about two weeks at cool room temperature; cut pieces keep two to three days covered in the fridge.

Using it

Eat watermelon fresh in wedges, cubed in salads with feta and mint, or blended into drinks and sorbet. The rind can be pickled.