Watermelon goes outside about two weeks after your last spring frost, once the soil is warm. It needs a long, hot season, so in the North transplants make a big difference. Find your zone below, or enter your ZIP code for dates based on the weather station closest to you.
Watermelon dates for your ZIP code
Planting times based on university extension guidance (UNH, Cornell, Purdue, Minnesota, Nebraska and UMass Extension). Frost dates from NOAA 1991–2020 U.S. Climate Normals, nearest weather station. Zones derived from the 2023 USDA Plant Hardiness Zone Map data (PRISM Climate Group, Oregon State University). This is not the official USDA Plant Hardiness Zone Map.
Watermelon planting dates by zone
| USDA zone | When to plant |
|---|---|
| Zone 3 | June 6 |
| Zone 4 | May 30 |
| Zone 5 | May 22 |
| Zone 6 | May 15 |
| Zone 7 | May 1 |
| Zone 8 | April 14 |
| Zone 9 | March 17 |
Not sure of your zone? Look it up by ZIP code.
Why watermelon waits for warm weather
Watermelon is a warm-season crop that needs warm soil and a long, hot summer. Frost kills it, and cool weather stalls its growth. That is why it goes out about two weeks after the last spring frost. Transplants started indoors give you a head start: they can be ready up to four weeks earlier than seeds sown in the garden.
How to plant watermelon
- Start seeds indoors about three to four weeks before transplanting, in individual pots.
- Lay black plastic or landscape fabric if you can, with a soaker hose underneath.
- Space plants 3–4 feet apart in rows 6–7 feet apart, or 2–3 plants per hill with hills 6–8 feet apart.
- Water well while the plants establish and the fruit grows.
- Cut back watering once the fruit starts to ripen.
Harvesting watermelon
Watermelons don’t ripen further after picking, so check carefully. A ripe melon has a yellowish underside where it touched the ground, a dead curly tendril next to the stem, and a dull sound when thumped instead of a metallic ring. Expect about 2–4 melons per plant.
Frequently asked questions
Can I plant watermelon before the last frost?
No. Frost kills watermelon, and it needs warm soil. Plant about two weeks after your last frost.
Should I start watermelon indoors?
It helps, especially in shorter seasons. Transplants can be ready up to four weeks earlier than direct-sown melons.
Why are my watermelons not setting fruit?
Usually poor pollination. Bees carry pollen to the female flowers, and they fly less in rainy weather. Avoid pesticides while vines bloom.
Sources. Planting dates use the median frost dates of each USDA zone, calculated from NOAA climate data for every ZIP code in the zone.