Sunlight: Full sun
Maturity: 70-90 days
Height: 1 to 2 feet
Spacing: 3 to 10 feet apart, 6 to 8 feet between rows
A heat-loving annual, watermelon can be grown in all parts of the country, but the warmer temperatures and longer season of southern areas especially favor this delicious crop. In cooler areas choose short-season varieties and do whatever it takes to protect vining plants from frost.
Fun Fact: Early explorers used this flavorful fruit to store water, similar to a canteen.
This great summer treat is even better when you grow it yourself.View all
- Choose a watermelon based on your climate — short-season varieties exist!
- Start seeds indoors or choose nutrient-rich soil outdoors in full sun
- Warm the soil and provide additional coverage for cooler weather
- Water and fertilize regularly for optimal results
- Provide plenty of space for vines and fruit
- Consult a clairvoyant to determine when to harvest — it’s an art form
- Pests and diseases include cucumber beetles, aphids, mites, squash bugs, fusarium wilt, anthracnose, alternaria leaf spot, and curly top
Choose a location where your plants will get full sun and good air circulation. A gentle, south-facing slope is ideal. Watermelons can grow in many kinds of soil, but prefer a light, sandy, fertile loam that drains easily. Add generous amounts of manure, compost and leaves to your garden and work the soil well prior to planting. Watermelons like lots of water, so keep the soil moist at all times.
How to Plant
In cooler climates, start seeds indoors 3-4 weeks before the last frost date and watch the weather carefully before planting outdoors.
For direct seeding, soak seeds in compost tea for 15 minutes prior to planting. Plant in hills 1/2 to 1 inch deep. For regular watermelon varieties, sow two to three seeds per hill, spacing the hills 8 to 10 feet apart. Thin seedlings in the hill to two seedlings one week after they have germinated. Small bush varieties may be spaced 3 feet apart.
If black or clear plastic was used to pre-warm the bed, cut holes in the plastic and set the plants 1/2 to 1 inch deeper than they were growing in their containers. Water thoroughly after transplanting.
Watermelons are heavy feeders. Apply an organic fertilizer during planting. Spray plants with liquid fertilizer and seaweed extract throughout the garden season. Cut back on nitrogen levels after flowers form. Continue with phosphorous and potassium applications until just before harvest.
Tip: Use Harvest Guard® row cover to warm the air and soil around heat-loving crops. It can also be used as a barrier to protect plants from invading pests.
Determining when to harvest watermelons can be difficult and requires some experience. For the most part when ripe, the curled tendril at the stem end dries to brown, the underside of the melon turns yellow or cream colored, and the melon will yield a deep, resonant sound when thumped.
Allow 80-90 days for bush varieties to reach maturity and 90-100 days or more for the larger varieties.
Insects and Diseases
Cucumber beetles, aphids, mites, squash bugs, fusarium wilt, anthracnose, alternaria leaf spot, and curly top are some of the problems home gardeners should be on the lookout for. Visit our Pest Problem Solver for pictures, descriptions and a complete list of safe, effective remedies.
Seed Saving Instructions
Watermelons will cross-pollinate, so isolate 1/2 mile from other varieties to maintain purity. When fruit is ready to eat, the seeds are also mature. Collect seeds and wash gently with a mild dishwashing soap. Rinse thoroughly and allow to dry.
Sup'r Green (3-2-2)
Sup'r Green provides over 5 times more plant food value than steer manure.
Floating row covers let in sun, water and air... but keep bugs out! Protects to 26°F.
Alaska MorBloom (0-10-10)
Use to stimulate exceptional budding and blooming on all flowering plants.