When to Plant Watermelon
The ultimate summer treat. Watermelons need heat, space, and patience — but the payoff is pure joy.
The Short Answer
How to Grow Watermelon
Watermelon tests your patience more than any other garden crop — the 80-100 day wait from transplant to ripe fruit feels interminable. The thump test is unreliable; instead, look for three signs: the tendril nearest the fruit turns brown, the ground spot (where the melon sits on soil) turns from white to creamy yellow, and the skin loses its gloss. Reduce watering in the last 10 days before harvest to concentrate sweetness. Watermelons won't continue ripening after harvest — unlike tomatoes, what you pick is what you get.
Starting Seeds Indoors
Begin watermelon seeds indoors 3 weeks before your average last frost date. Seeds need soil temperatures of at least 70°F to germinate, which typically takes 5-10 days. Provide 12 hours of light per day using a south-facing window or grow lights.
Transplanting
Move seedlings outside 2 weeks after your last frost date, once soil temperatures reach 70°F. Harden off seedlings for 7 days before transplanting by gradually exposing them to outdoor conditions.
Direct Sowing
Watermelon can be direct sown 3 weeks after your last frost date. Plant seeds 1" deep, spaced 72" apart.
Growing Tips
Black plastic mulch warms soil faster. Check ripeness by looking for a yellow ground spot and listening for a hollow thump.
Companion Planting
Good companions:
Keep away from:
Watermelon Planting Dates by State
Click your state for watermelon planting dates specific to your location:
Last reviewed: March 29, 2026