How to grow watermelon
Citrullus lanatus · Cucurbitaceae · Fruit
When to plant watermelons: the short answer
Start seeds indoors about 3 weeks before your last spring frost; plant out about 2 weeks after it; sow outdoors about 2 weeks after the last frost. Wait until the soil is at least 70°F; watermelons sprout fastest near 85°F.
Zone 5: plant out May 7 – May 24. Zone 7: plant out Apr 12 – Apr 29. Zone 9: plant out Feb 27 – Mar 16. See every zone.
Watermelon is a warm-season fruiting crop in the Cucurbitaceae family, grown either from a direct sowing or from transplants. It wants full sun (six or more hours of direct light) and steady, even moisture. From sowing to first pick is about 70–100 days. It is killed by frost, so nothing goes outside until the danger has passed and the soil has warmed.
Grower’s note: Longest-season cucurbit here - icebox varieties (70-75 days) are the realistic choice north of the mid-Atlantic. Ripe when the curly tendril nearest the fruit is brown and dry and the ground spot is buttery yellow.
Sowing
Sow about 1″ deep, into soil between 70–95°F — germination is quickest near 85°F. It comes up fast (4–10 days). For an early crop, start seed indoors about 3 weeks before your last spring frost and grow it under bright light.
Spacing & layout
Give each plant about 36″ along the row with roughly 72″ between rows. On a square-foot grid that is one plant per 4 square feet. Allow at least 24″ of loose, workable soil for the roots. It needs more root room than most containers give and does best in the ground.
Fitting it to your season
Watermelon needs roughly 70–100 frost-free days to crop. Where the season is shorter than that, start it indoors and choose the earliest-maturing varieties, or grow it in a container you can move under cover on cold nights. In long, hot-summer regions it can often be planted twice — once in spring and again in mid-to-late summer for a fall harvest.
Quick facts
Growth stages: how long watermelons take to grow
From sowing to first harvest takes roughly 70-100 days (10-14 weeks), with seedlings appearing after 4-10 days in soil around 85°F.
When to plant watermelon
When to plant watermelons by USDA zone
Dates worked out from each zone’s typical frost dates for 2026. Find your zone on the zone map, or pick your state below for dates from its own frost dates. Zones 11 and above are frost-free, so timing there depends on heat and rain instead.
| Zone | Last / first frost | Start indoors | Sow or plant out |
|---|---|---|---|
| Zone 3 | May 15 / Sep 15 | Apr 17 – May 1 | May 22 – Jun 8 |
| Zone 4 | May 10 / Sep 25 | Apr 12 – Apr 26 | May 17 – Jun 3 |
| Zone 5 | Apr 30 / Oct 5 | Apr 2 – Apr 16 | May 7 – May 24 |
| Zone 6 | Apr 15 / Oct 15 | Mar 18 – Apr 1 | Apr 22 – May 9 |
| Zone 7 | Apr 5 / Oct 25 | Mar 8 – Mar 22 | Apr 12 – Apr 29 |
| Zone 8 | Mar 20 / Nov 5 | Feb 20 – Mar 6 | Mar 27 – Apr 13 |
| Zone 9 | Feb 20 / Nov 30 | Jan 23 – Feb 6 | Feb 27 – Mar 16 |
| Zone 10 | Jan 30 / Dec 15 | Jan 2 – Jan 16 | Feb 6 – Feb 23 |
Or browse watermelon planting dates for every state as static pages.
Companions
Sweet Corn, Bush Bean, Radish
Potato
Common problems
Pests: striped cucumber beetle, aphids, squash vine borer.
Diseases & disorders: anthracnose, fusarium wilt, powdery mildew, gummy stem blight.
Same family (Cucurbitaceae)
Rotate these so they don’t follow each other in the same bed year to year.
Questions gardeners ask
When should I plant watermelons?
Start seeds indoors about 3 weeks before your last spring frost; plant out about 2 weeks after it; sow outdoors about 2 weeks after the last frost. Wait until the soil is at least 70°F. The table on this page gives dates for each USDA zone, and the planting calendar gives dates for your own state or ZIP code.
How long do watermelons take to grow?
About 70-100 days from sowing to the first harvest. Seeds germinate in 4-10 days, fastest in soil around 85°F.
How much sun do watermelons need?
They need at least six to eight hours of direct sun a day.
What soil pH do watermelons need?
A soil pH between 5.5 and 6.8. It tolerates fairly acidic soil better than most vegetables. Test before adding lime or sulfur - see the soil pH and testing guide.
How far apart should I plant watermelons?
Space plants about 36 inches apart in rows 72 inches apart, or one plant per 4 square feet in a square-foot bed. Sow seeds about 1 inch deep.
Can I grow watermelons in a container?
It is not well suited to containers - it needs more root room and space than a pot gives, so grow it in a bed.
Figures are typical home-garden ranges from Cooperative Extension planting guides, cross-checked against multiple state sources. Your variety and conditions will vary.