How to Grow Watermelon

Growing guide

Overview

Watermelon is a warm-season annual vine grown for its large, sweet, juicy fruit. Gardeners love it for summer harvests and compact icebox types for smaller spaces. To thrive it needs full sun, consistent moisture, warm soil, and room to sprawl or a large container.

Soil & planting prep

Plant in sandy or loamy, well-drained soil with a pH of 6.0-6.8. Sow seeds 1 inch deep, or set transplants at the same depth as their pots. Space bush/icebox plants about 3 feet apart and vining types 4-6 feet apart in rows 6-8 feet apart.

When to plant

Start seeds indoors 4 weeks before your last spring frost date. Transplant outdoors only after all danger of frost has passed and the soil has warmed to at least 65°F, usually 1-2 weeks after the last frost. Watermelon is frost tender and is not planted in fall.

How to plant

1. Start seeds indoors 4 weeks before your last frost date in individual biodegradable pots, planting seeds 1 inch deep in warm soil.
2. Harden off seedlings for a week and prepare a full-sun bed with well-drained sandy or loamy soil at pH 6.0-6.8.
3. Transplant after the last frost when soil is at least 65°F, spacing bush/icebox types 3 feet apart and vining types 4-6 feet apart.
4. Water plants at the base with about 1-2 inches per week during growth, keeping soil evenly moist but not soggy.
5. Apply black plastic mulch or straw early in the season to warm the soil, reduce weeds, and keep developing fruit clean.

5 common mistakes to avoid

• Starting watermelon seeds too early indoors produces leggy, root-bound transplants; start only 4 weeks before your last frost date.
• Transplanting into cold soil below 65°F stalls growth and can cause roots to rot; wait until soil has warmed after the last frost.
• Disturbing watermelon roots during transplant shock can set plants back badly; start in biodegradable pots and handle the root ball gently.
• Letting soil dry out during flowering and fruit swelling leads to cracked, small, or poorly flavored melons; keep moisture steady until fruit nears full size.
• Growing vining watermelons in crowded beds reduces airflow, invites foliar disease, and produces smaller fruit; give vining types 4-6 feet of space or choose a bush/icebox variety.

Harvesting & storage

Watermelons are ready about 70-90 days after transplant when the curly tendril nearest the fruit turns brown and dry, the ground spot changes from white to creamy yellow, and the rind loses its shine. Cut the stem with pruners, leaving about 1 inch attached. Store whole melons in a cool spot at 50-60°F for up to 2-3 weeks; refrigerate cut fruit and use within 3-5 days.

Companion planting

Good companions include bush beans, radishes, lettuce, and nasturtiums, which can use space early or attract beneficial insects. Avoid planting watermelon next to cucumbers, squash, and potatoes to reduce shared pests and disease pressure.

Growing in containers

Watermelon can grow in a 15-gallon container if you select a compact or icebox variety. Use a strong trellis to support the vines, keep the container in full sun, and water consistently during hot weather.

Pro tips

Start indoors 4 weeks before last frost. Transplant carefully — watermelons hate root disturbance. Give them maximum space. Use black plastic mulch to warm soil. Choose icebox varieties for containers.