Maine planting calendar

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

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

Thyme planting timetable for Maine

Stage	When in Maine	Anchor
Start seeds indoors	mid-March (March 20)	8 weeks before the last frost (mid-May)
Transplant outside	mid-May (May 15)	0 days after the last frost (mid-May)
First harvest (estimate)	early August (August 8)	~85 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 thyme 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. Wait for warm soil — thyme stall in cold ground even after the air warms, so don't rush them out.

Start seeds indoors 8–10 weeks before the last spring frost; germination takes 14–21 days at 18–21 °C (65–70 °F). Harden off transplants and set out around the date of last frost — thyme is perennial in USDA zones 5–9 (RHS H5) but resents waterlogged soil far more than cold. In the first growing season allow only light harvesting so the plant can establish; full harvests from the second year onward, cutting stems back to 4–5 cm above woody growth.

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

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

Quick-grow guide

Sun: Full sun — 6+ hours direct.
Soil temperature for germination: 18–21 °C (65–70 °F).
Spacing: 6–8 inches (15–20 cm) between plants.
Days to harvest: ~85 days from planting out.

Frequently asked questions

When is the best time to plant thyme in Maine?

In Maine (mostly USDA zone 5a), sow thyme indoors around mid-March, transplant outdoors mid-May (after the last frost, mid-May), and harvest from early August. Thyme 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 thyme in Maine?

Yes. Maine's dominant zone 5a supports thyme — the key is timing. Thyme 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?

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.