To grow watermelon from seed, follow these key steps:
Seed Starting and Soil Preparation
- Sow watermelon seeds about 1 to 2 cm (around 1 inch) deep in warm soil or seed compost. Ideal soil temperature for germination is between 18°C and 32°C (65°F to 90°F)
- If starting indoors, sow seeds in peat-free seed compost in pots or seed trays, keeping them in a heated propagator or warm spot (18-21°C). Seedlings should emerge in 7-14 days
- For outdoor planting, wait until after the last frost and when soil temperatures reach at least 18°C (65°F) at 4 inches deep
Planting Location and Soil Conditions
- Choose a sunny, sheltered spot with well-drained, nutrient-rich soil amended with organic matter like compost or well-rotted manure
- Watermelons need plenty of space to grow due to their spreading vines. Space hills or mounds about 1.2 to 1.8 meters (4 to 6 feet) apart, with rows spaced similarly
Planting Method
- Create mounds or hills about 8-12 inches high and 2-3 feet in diameter. Sow 5-8 seeds per hill, then thin to 3-4 strong plants once seedlings have established
- Water seeds gently after planting to keep soil moist but not waterlogged
Growing Conditions and Care
- Watermelons require consistent moisture, about 1 to 2 inches per week, especially during flowering and fruit development
- Protect young seedlings from pests, pets, and harsh weather until established
- If growing vertically on trellises, support fruits with slings to prevent breakage
- Harden off indoor seedlings before transplanting outdoors by gradually exposing them to outdoor conditions over 1-2 weeks
Additional Tips
- If you have a short growing season, start seeds indoors to get a head start and transplant after frost danger passes
- Choose faster-maturing varieties if your climate has a shorter summer
- Monitor for common diseases like powdery mildew and use row covers early in the season to protect plants
By following these steps, you can successfully grow watermelons from seed and enjoy fresh, homegrown fruit by late summer or early fall
