Missouri planting calendar

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

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

Leeks planting timetable for Missouri

Stage	When in Missouri	Anchor
Start seeds indoors	early February (February 4)	10 weeks before the last frost (mid-April)
Transplant outside	mid-March (March 18)	28 days before the last frost (mid-April)
First harvest (estimate)	mid-July (July 16)	~120 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 leeks 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. Sow early — leeks bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Leeks are among the hardiest alliums — established plants tolerate temperatures as low as -10 °C, making them a reliable overwintering crop in zones 5–9. Start seeds indoors 10–12 weeks before last frost, transplanting pencil-thick seedlings into 15 cm (6-inch) deep holes or trenches to blanch the stems; backfill gradually as plants grow. Early-season varieties mature in around 90 days; late-season types take up to 150 days and deliver the best cold-hardiness for autumn and winter harvest.

Frost-risk note

Don't plant before mid-April — a hard freeze can still set young plants back. 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

The same early window suits peas, lettuce, spinach, and onion sets.

Quick-grow guide

Sun: Full sun — 6+ hours direct.
Soil temperature for germination: 7-25 °C (45-77 °F).
Spacing: 6 inches (15 cm) between plants.
Days to harvest: ~120 days from planting out.

Frequently asked questions

When is the best time to plant leeks in Missouri?

In Missouri (mostly USDA zone 6b), sow leeks indoors around early February, transplant outdoors mid-March (before the last frost, mid-April), and harvest from mid-July. Leeks are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

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 leeks in Missouri?

Yes. Missouri's dominant zone 6b supports leeks — the key is timing. Leeks are cold-hardy — they tolerate frost and actively prefer cool weather, so they go in well before the last spring frost and bolt in summer heat.

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?

The same early window suits peas, lettuce, spinach, and onion sets.

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.