Oklahoma planting calendar

When to plant collard greens in Oklahoma — sow, transplant & harvest dates

Oklahoma is mostly USDA zone 7b (range 6b-8a). Dates below are derived from collard greens's frost tolerance and Oklahoma's frost window — not generic national averages.

Collard Greens planting timetable for Oklahoma

Stage	When in Oklahoma	Anchor
Start seeds indoors	early March (March 8)	4 weeks before the last frost (early April)
Transplant outside	mid-March (March 15)	21 days before the last frost (early April)
First harvest (estimate)	late May (May 24)	~70 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 Oklahoma's climate shifts the collard greens dates

Oklahoma's last spring frost averages early April and first fall frost late October, which sets the whole planting clock. Oklahoma has a long, hot, often windy season. Summer heat and drought stress are as limiting as the winter low across most of the state. Sow early — collard greens bolt once daytime temperatures hold above 24 °C, so the earlier they go in, the longer the harvest.

Collards are one of the hardiest brassicas, tolerating temperatures down to about -7 °C once established, and one of the most heat-tolerant — unlike kale or cabbage, they continue producing in summer heat above 32 °C, which is why they are a staple in Zones 7–9 year-round. Transplant 2–4 weeks before last spring frost, or direct-sow where the season allows; for a fall harvest, start transplants 8–10 weeks before first fall frost. Succession-plant for continuous leaf harvest.

Frost-risk note

Don't plant before early April — a hard freeze can still set young plants back. In the Panhandle High Plains (zone 6b) the safe date runs a week or two later.

Regional variation within Oklahoma

the Panhandle High Plains (zone 6b) runs roughly 1-2 weeks behind the state average; the south-central and southeast lowlands (zone 8a) can plant 1-2 weeks earlier.

Oklahoma City — USDA zone 7b
Tulsa — USDA zone 7b
Norman — USDA zone 7b
Lawton — USDA zone 8a

What else to plant in Oklahoma 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: 7-29 °C (45-85 °F).
Spacing: 18-24 inches (45-60 cm) between plants.
Days to harvest: ~70 days from planting out.

Frequently asked questions

When is the best time to plant collard greens in Oklahoma?

In Oklahoma (mostly USDA zone 7b), sow collard greens indoors around early March, transplant outdoors mid-March (before the last frost, early April), and harvest from late May. Collard Greens 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 Oklahoma?

Most of Oklahoma sits in USDA hardiness zone 7b, with the state spanning roughly 6b-8a from the Panhandle High Plains (zone 6b) to the south-central and southeast lowlands (zone 8a). The last spring frost averages early April and the first fall frost late October.

Can you grow collard greens in Oklahoma?

Yes. Oklahoma's dominant zone 7b supports collard greens — the key is timing. Collard Greens 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 Oklahoma?

the Panhandle High Plains (zone 6b) runs roughly 1-2 weeks behind the state average; the south-central and southeast lowlands (zone 8a) can plant 1-2 weeks earlier.

What else can I plant in Oklahoma 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.