Missouri planting calendar

When to plant watermelon in Missouri — sow, transplant & harvest dates

Missouri is mostly USDA zone 6b (range 5b-7a). Dates below are derived from watermelon's frost tolerance and Missouri's frost window — not generic national averages.

Watermelon planting timetable for Missouri

Stage	When in Missouri	Anchor
Start seeds indoors	mid-March (March 18)	4 weeks before the last frost (mid-April)
Transplant outside	late April (April 29)	14 days after the last frost (mid-April)
First harvest (estimate)	mid-July (July 18)	~80 days from transplant

Dates are state-wide averages for the dominant zone. Local microclimates — elevation, urban heat, coastal moderation — can shift the window by 1-2 weeks. Use the frost-date calculator for a date tuned to your town.

Why Missouri's climate shifts the watermelon dates

Missouri's last spring frost averages mid-April and first fall frost mid-October, which sets the whole planting clock. Missouri has a humid continental climate with hot summers and a southeastern Bootheel that gardens nearly a zone warmer than the north. Wait for warm soil — watermelon stall in cold ground even after the air warms, so don't rush them out.

Start seeds indoors 3–5 weeks before last frost; transplant only after all frost danger is gone and soil is consistently 65–70 °F (18–21 °C) — cold soil causes stunted growth and root rot. Days to harvest range 70–90 from transplant depending on variety (icebox types ~70 days, full-size ~85–90 days). In zones 9–11 direct sowing is practical; in zones 3–5 choose early-maturing varieties (≤80 days) to beat first fall frost.

Frost-risk note

Don't plant before mid-April — even a light frost will kill seedlings overnight. In the northern counties near Iowa (zone 5b) the safe date runs a week or two later.

Regional variation within Missouri

the northern counties near Iowa (zone 5b) runs roughly 1-2 weeks behind the state average; the Bootheel in the southeast (zone 7a) can plant 1-2 weeks earlier.

Kansas City — USDA zone 6b
St. Louis — USDA zone 7a
Springfield — USDA zone 7a
Columbia — USDA zone 6b

What else to plant in Missouri around then

Pair the post-frost slot with other warm-season crops — peppers, beans, squash, and cucumbers.

Quick-grow guide

Sun: Full sun — 8+ hours direct.
Soil temperature for germination: 21–35 °C (70–95 °F).
Spacing: 36–48 inches (90–120 cm) in-row; 72–96 inches (180–240 cm) between rows between plants.
Days to harvest: ~80 days from planting out.

Frequently asked questions

When is the best time to plant watermelon in Missouri?

In Missouri (mostly USDA zone 6b), sow watermelon indoors around mid-March, transplant outdoors late April (after the last frost, mid-April), and harvest from mid-July. Watermelon are frost-tender — a single light frost kills seedlings, so they only go outside once frost danger has fully passed and the soil is warm.

What USDA zone is Missouri?

Most of Missouri sits in USDA hardiness zone 6b, with the state spanning roughly 5b-7a from the northern counties near Iowa (zone 5b) to the Bootheel in the southeast (zone 7a). The last spring frost averages mid-April and the first fall frost mid-October.

Can you grow watermelon in Missouri?

Yes. Missouri's dominant zone 6b supports watermelon — the key is timing. Watermelon are frost-tender — a single light frost kills seedlings, so they only go outside once frost danger has fully passed and the soil is warm.

Does the planting date change across Missouri?

the northern counties near Iowa (zone 5b) runs roughly 1-2 weeks behind the state average; the Bootheel in the southeast (zone 7a) can plant 1-2 weeks earlier.

What else can I plant in Missouri around the same time?

Pair the post-frost slot with other warm-season crops — peppers, beans, squash, and cucumbers.

Source and methodology

State zone spans from the USDA Plant Hardiness Zone Map (2023); frost-date averages from NOAA Climate Data Online. Hot-state two-season timing cross-checked against the UF/IFAS Florida Gardening Calendar and the University of Arizona Cooperative Extension planting calendar. Curated by the Growli editorial team.