Maine planting calendar

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

Maine is mostly USDA zone 5a (range 3b-6a). Dates below are derived from collard greens's frost tolerance and Maine's frost window — not generic national averages.

Collard Greens planting timetable for Maine

Stage	When in Maine	Anchor
Start seeds indoors	mid-April (April 17)	4 weeks before the last frost (mid-May)
Transplant outside	late April (April 24)	21 days before the last frost (mid-May)
First harvest (estimate)	early July (July 3)	~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 Maine's climate shifts the collard greens dates

Maine's last spring frost averages mid-May and first fall frost late September, which sets the whole planting clock. Maine is a short-season cold-climate state, milder along the coast and noticeably colder in the northern and mountain interior. 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 mid-May — a hard freeze can still set young plants back. In the far north Aroostook County interior (zone 3b) the safe date runs a week or two later.

Regional variation within Maine

the far north Aroostook County interior (zone 3b) runs roughly 1-2 weeks behind the state average; the southern coast around Portland (zone 6a) can plant 1-2 weeks earlier.

Portland — USDA zone 6a
Bangor — USDA zone 5a
Augusta — USDA zone 5b
Presque Isle — USDA zone 4a

What else to plant in Maine 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 Maine?

In Maine (mostly USDA zone 5a), sow collard greens indoors around mid-April, transplant outdoors late April (before the last frost, mid-May), and harvest from early July. 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 Maine?

Most of Maine sits in USDA hardiness zone 5a, with the state spanning roughly 3b-6a from the far north Aroostook County interior (zone 3b) to the southern coast around Portland (zone 6a). The last spring frost averages mid-May and the first fall frost late September.

Can you grow collard greens in Maine?

Yes. Maine's dominant zone 5a 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 Maine?

the far north Aroostook County interior (zone 3b) runs roughly 1-2 weeks behind the state average; the southern coast around Portland (zone 6a) can plant 1-2 weeks earlier.

What else can I plant in Maine 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.