How to Plant, Grow, and Harvest Watermelon

When to Plant Watermelons

• In cool climates with short growing seasons, start seeds indoors 2 to 3 weeks before your last frost date. Plan to transplant seedlings into the garden about 2 weeks after that date or when the soil has warmed to at least 65°F (18°C).
• In warmer climates with long growing seasons, sow seeds directly outdoors 1 to 2 weeks after your last frost date, as long as the soil temperature has warmed to at least 65°F (18°C).
• Young watermelon plants can also be bought from nurseries. Plant these after there is no longer a chance of frost; they are very tender. Watch the local forecast and err on the side of caution! Consider laying black plastic over your planting area to warm the soil even more.
  • Tip: Starting with young plants can result in an earlier harvest (usually up to 2 weeks earlier), so consider buying young plants, particularly if you live in a cooler climate.

Choosing and Preparing a Planting Site

• Amend soil with aged manure, seaweed, and/or compost before planting. Watermelons are heavy feeders, meaning they need soil that is fertile and has a high nutrient level. Learn more about soil amendments and preparing soil for planting.
• Watermelons do best in loamy, somewhat sandy, well-drained soil. They can struggle in soil that contains too much clay and doesn’t drain well.
• Watermelons prefer a soil pH between 6.0 and 7.5 (“slightly acidic to neutral”).
• Watermelons need A LOT of space—up to 20 square feet per plant. Their vines need room to sprawl, so plant them in a place where they won’t crowd out other crops.
• Growing the vines in raised rows, known as hills, ensures good drainage and will hold the sun’s heat longer.
  • Plan to space the plants 2-3 feet apart in a 5-foot-wide hill.
  • If you’re growing in traditional rows, space them at least 6 feet apart. 

How to Plant Watermelons

• Sow seeds 1/2 to 1 inch deep outdoors or 1/4 to 1/2 inch deep in seed-starting pots indoors.
  • Tip: To allow for more root growth, use larger starting pots than you would for most seeds. Also, consider using compostable pots that can be cut away or planted directly in the garden, as this will minimize the risk of damaging seedlings’ tender roots during transplanting.
• If direct seeding outdoors, sow 4 to 6 seeds per hill, eventually thinning to 2 to 3 seedlings. 

Transplanting Seedlings

• Handle watermelon seedlings with extreme care when you transplant. Their roots are very fragile, so try not to disturb the soil when removing them from pots.
• After transplanting, cover the plants with row covers to keep pests at bay. Remember to remove the row covers when you see both male and female flowers on the vine, as pollinators will need to access the flowers.
• Find even more tips for planting melons in your home garden.