When to plant watermelons by city
Start watermelons indoors 3–4 weeks before your last frost, plant them out 2–4 weeks after your last frost, or sow seed outdoors 2–4 weeks after your last frost, once the soil is at least 70°F. Here is what that means for 2027 in cities across the US, using each city’s average frost dates and the date its normal daily temperature reaches 65°F, so cool-spring places like Seattle wait for real warmth (NOAA 1991–2020). Pick the city with the climate most like yours, or enter your ZIP code above.
| City | Last frost | Start indoors | Plant out | Sow outdoors |
|---|---|---|---|---|
| Seattle, WA (9a) | Mar 13 | May 19–26 | Jun 30 – Jul 14 | Jun 30 – Jul 14 |
| Portland, OR (8b) | Feb 25 | May 14–21 | Jun 25 – Jul 9 | Jun 25 – Jul 9 |
| Sacramento, CA (9b) | Jan 12 | Mar 21–28 | May 2–16 | May 2–16 |
| Phoenix, AZ (10a) | Jan 5 | Jan 26 – Feb 2 | Mar 9–23 | Mar 9–23 |
| Salt Lake City, UT (7b) | Mar 31 | Apr 12–19 | May 24 – Jun 7 | May 24 – Jun 7 |
| Denver, CO (6a) | Apr 30 | Apr 18–25 | May 30 – Jun 13 | May 30 – Jun 13 |
| Dallas, TX (8b) | Mar 2 | Feb 23 – Mar 2 | Apr 6–20 | Apr 6–20 |
| Minneapolis, MN (5a) | Apr 23 | Apr 22–29 | Jun 3–17 | Jun 3–17 |
| Kansas City, MO (6b) | Apr 4 | Mar 29 – Apr 5 | May 10–24 | May 10–24 |
| Chicago, IL (6b) | Apr 10 | Apr 25 – May 2 | Jun 6–20 | Jun 6–20 |
| Columbus, OH (6b) | Apr 20 | Apr 11–18 | May 23 – Jun 6 | May 23 – Jun 6 |
| Nashville, TN (7b) | Apr 1 | Mar 24–31 | May 5–19 | May 5–19 |
| Atlanta, GA (8a) | Mar 24 | Mar 16–23 | Apr 27 – May 11 | Apr 27 – May 11 |
| Raleigh, NC (8a) | Mar 28 | Mar 20–27 | May 1–15 | May 1–15 |
| Philadelphia, PA (7b) | Mar 30 | Mar 31 – Apr 7 | May 12–26 | May 12–26 |
| Boston, MA (7a) | Apr 4 | Apr 24 – May 1 | Jun 5–19 | Jun 5–19 |
In frost-free parts of Florida, southern California and the Gulf Coast, timing is about heat instead: plant watermelons in late winter or early spring and again in late summer.
Don’t go by the calendar alone. Watermelons planted into cold soil sit still for weeks; wait until the soil 4 inches down is at least 70°F and nights stay above 50°F.
Watermelon spacing
In a square-foot bed, plant one plant per 9 square feet (a 3 × 3 ft block). In traditional rows, space plants about 48 inches apart with 72 inches between rows.
Needs the longest, hottest summer of the melons. Icebox types fit small gardens.
How to grow watermelons
Watermelons need the longest, hottest summer of the melons and plenty of ground. Southern gardeners have it easiest, but small icebox varieties ripen sooner and fit modest gardens farther north.
Sun and soil
Full sun and warm, sandy, well-drained soil, pH about 6.0–6.8. Most roots are in the top foot of soil; water deeply and consistently, 1–2 inches a week, through fruit set.
Planting
- Sow 1 inch deep once soil is 70°F, usually 2–4 weeks after the last frost, or transplant 3–4-week-old seedlings then.
- Seedless varieties germinate poorly in cool soil; start them indoors somewhere very warm and plant a seeded variety nearby, since they need its pollen.
- Space 48 inches apart in rows 72 inches apart.
Care
- Use drip irrigation if you can, or water in the morning.
- Keep nitrogen moderate; too much gives huge vines and few melons.
- Uncover row covers at bloom, and water less as fruit nears ripeness.
Harvest
Melons ripen about 35 days after fruit set. Look for three signs: the tendril nearest the fruit is brown and dry, the ground spot has turned from white to creamy yellow, and the rind has gone from shiny to dull. Thumping is less reliable.
Common problems
- Anthracnose and gummy stem blight: Dark spots on leaves, stems and fruit. Rotate cucurbits for 3 years, water at the base, and clear vines after harvest.
- Misshapen or few fruit: Poor pollination. Avoid insecticides during morning bloom.
- Blossom-end rot: Keep soil evenly moist, not soggy.
Varieties to try
- 'Crimson Sweet' — large, striped, red flesh
- 'Sugar Baby' — dark green icebox type
- 'Mickylee' — small gray-green icebox type
- 'Yellow Baby' — small, yellow flesh
Crop rotation
Watermelons belong to the squash family (Cucurbitaceae). Heavy feeders. Cucumber beetles and powdery mildew carry over between years. Relatives that count as the same family for rotation: cucumber, zucchini, yellow squash, winter squash, pumpkin, cantaloupe.
Frequently asked questions
When should I plant watermelons?
What should not be planted with watermelons?
How far apart should I plant watermelons?
How long do watermelons take to grow?
Can watermelons handle frost?
Sources
- Frost dates: NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020.
- Hardiness zones: 2023 USDA Plant Hardiness Zone Map, USDA-ARS and PRISM Climate Group, Oregon State University.
- Planting windows and spacing: Vegetable Planting Guide (GardenNotes #720), Colorado State University Extension, and other land-grant extension guides.
- Watermelon — Clemson Cooperative Extension (HGIC)
- Watermelon in the Garden — Utah State University Extension