Generally — Most Areas
skirret (zones 5-9) suits most of Maine (3b-7a) — zones 5-7 are in range, and the rest of the state is the exception.
Skirret in Maine — the short answer
Skirret in Maine: hardy in zones 5–9, part sun, against a state median of ~182 frost-free days.
- Plant zones
- 5-9
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Maine zones
- 3b-7a
- USDA PHZM 2023
- Frost window
- Apr 16 - May 3 – Oct 10 - Oct 24
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 143 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Maine spans zones 3b-7a, but your yard has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score skirret against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Maine is not one climate
A single Maine answer averages 16 counties whose growing seasons are 79 days apart — from 143 frost-free days in Franklin County to 222 in Knox County. Which end of that your land sits nearer changes what skirret can finish before the first hard freeze.
The middle half of 16 counties runs 154–191 days, with a median of 178 days — a 79-day span end to end.
Measured across 16 Maine counties. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Maine Fits Best
Skirret is rated for zones 5–9 — a cold floor USDA puts at -20 to -10°F. Against Maine’s 16 counties that band holds in 12 of them, and the line runs at Oxford County (zone 5a), the coldest county still inside it.
Inside zones 5–9
12 counties
- Penobscot County · zone 5a
- Androscoggin County · zone 5b
- Cumberland County · zone 5b
3 of 12 shown
Below the zone 5 floor
4 counties
- Aroostook County · zone 4a
- Franklin County · zone 4b
- Piscataquis County · zone 4b
3 of 4 shown
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Even within Maine's zones 3b-7a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for skirret (USDA PHZM 2023):
Zone Comparison
Skirret Needs
- USDA Zones: 5-9
- Frost-Free Days: 40+
- Sun: Part Sun
Maine Has
- USDA Zones: 3b-7a
- Last Hard Freeze (28°F): Apr 16 - May 3
- First Hard Freeze (28°F): Oct 10 - Oct 24
- Annual Rainfall: 36-50 inches
- Common Soils: Glacial till, Sandy loam, Rocky loam
Plant Zone Range (zones 5-9)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Skirret in Maine
The frost window
Across Maine, the last spring hard freeze (28°F) clears between Apr 16 and May 3, and the first fall hard freeze lands between Oct 10 and Oct 24 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 160-day window you can count on — up to 191 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
When to start the seed
Those dates are when skirret goes out, not when it starts. It is sown under cover about 6 weeks ahead, so counting back from Maine's late-side last freeze of May 3 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says skirret survives winter in part of Maine, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Skirret wants 40+ frost-free days; a typical Maine site sees ~182 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Skirret likes near-neutral soil (pH 5.5-7.5). That's the common-ground band across Maine's glacial till and sandy loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6 and 6.8 — worth knowing before you decide whether a Maine soil test result is a problem or just a number. Drainage matters: this plant wants poorly (saturated >50% of year), well (dry spells). If your Maine site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Maine soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant skirret for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before skirret goes in. What follows is Maine’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Maine — and how to grow with it.
We checked the federal record across Maine — 10,103 documented sites across 8 of the 9 source types we track.
The most significant on record: 99 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Maine carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources Checked
across Maine
Severity Distribution
across Maine
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What Else to Consider for Skirret in Maine
Zone compatibility tells you about winter cold survival — but Maine growers also need to think about:
Very short growing season (100-140 frost-free days)
Rocky glacial soils require significant clearing
Harsh winters with heavy snow and ice
What to actually do about these — and the constraints that apply to every Maine grower, not just skirret — is covered on the Maine growing guide.
Timing shifts within Maine
Skirret needs about 40 days of frost-free season to complete its cycle. Even Franklin County — Maine’s shortest season at 143 frost-free days — clears that by 103 days, so season length isn’t the constraint anywhere in Maine. What varies is your own parcel.
Across Maine’s 16 counties the frost-free season runs from 143 days in Franklin County to 222 days in Knox County — a spread of 79 days, which is why a single statewide planting date misleads. The median Maine county sees 182 frost-free days, leaving skirret about 142 days of slack on a typical parcel — room for a second sowing where the season runs long.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Skirret's 40-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Skirret draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, skirret can only work that bloom inside Maine's frost window — roughly 182 days, opening after the last 28°F freeze (Apr 16 - May 3) and closing at the first (Oct 10 - Oct 24), per NOAA Regional Climate Centers ACIS, 1991-2020.
Maine Cooperative Extension
For Maine-specific cultivar recommendations, planting calendars, and pest pressure for skirret, the canonical source is UMaine Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Skirret in Maine
When can I plant Skirret in Maine?
Maine's last spring hard freeze (28°F) clears between Apr 16 and May 3, and the first fall hard freeze lands between Oct 10 and Oct 24 (NOAA Regional Climate Centers ACIS, 1991-2020). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
What hardiness zone is Skirret grown in across Maine?
Maine spans USDA hardiness zones 3b-7a (USDA ARS PHZM 2023). Skirret carries a range of zones 5-9, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Maine site have?
A typical Maine site sees ~182 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Skirret needs 40+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
How should I amend the soil for Skirret in Maine?
Skirret prefers pH 5.5-7.5 and poorly (saturated >50% of year), well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Maine soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Skirret actually grow on my specific land in Maine?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores skirret against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Maine
State-level data is a sketch. Your Growable Ground report scores skirret against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Maine skirret averages can't show:
We read public map data around Maine — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Maine skirret average
Explore More
Growing guides for skirret
Explore Maine county by county
Maine carries 16 counties with their own USDA zone — a sample of the growing pages for skirret there:
Where else skirret grows
Skirret's zone band crosses state lines — these are the states closest to Maine in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Maine
Maine has a growing page for 806 plants — a rotating sample of the rest of the shelf.
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