Missouri planting calendar

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

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

Sweet potatoes planting timetable for Missouri

Stage	When in Missouri	Anchor
Start seeds indoors	early March (March 4)	6 weeks before the last frost (mid-April)
Transplant outside	early May (May 6)	21 days after the last frost (mid-April)
First harvest (estimate)	mid-August (August 19)	~105 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 sweet potatoes 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 — sweet potatoes stall in cold ground even after the air warms, so don't rush them out.

Sweet potatoes are extremely frost-tender and demand warm soil — do not transplant slips until soil temperature at 4-inch depth holds at 18 °C (65 °F) or above, typically 3 weeks after the last spring frost. Short-season zones (z5-6) should start slips indoors under lights 5-6 weeks early to ensure 100-120 frost-free days. Avoid zones 3-4 without a floating row cover season-extension strategy; in z9-11 slips can go out as early as late March.

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 — 6-8 hours direct.
Soil temperature for germination: Soil 18-24 °C (65-75 °F) for slip rooting.
Spacing: 12-18 inches (30-45 cm) between plants.
Days to harvest: ~105 days from planting out.

Frequently asked questions

When is the best time to plant sweet potatoes in Missouri?

In Missouri (mostly USDA zone 6b), sow sweet potatoes indoors around early March, transplant outdoors early May (after the last frost, mid-April), and harvest from mid-August. Sweet potatoes 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 sweet potatoes in Missouri?

Yes. Missouri's dominant zone 6b supports sweet potatoes — the key is timing. Sweet potatoes 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.