Conditional — Some Areas
autumn fern (zones 6-8) reaches only part of Maine (3b-7a): zones 6-7 are in range, so where you are in the state decides it.
Autumn Fern in Maine — the short answer
Autumn Fern in Maine: hardy in zones 6–8, part sun, against a state median of ~182 frost-free days.
- Plant zones
- 6-8
- 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 autumn fern against your land's actual soil, sun, and frost.
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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 autumn fern 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
Autumn Fern is rated for zones 6–8 — a cold floor USDA puts at -10 to 0°F. Against Maine’s 16 counties that band holds in 2 of them, and the line runs at Knox County (zone 6a), the coldest county still inside it.
Inside zones 6–8
2 counties
0 of 2 shown
Below the zone 6 floor
14 counties
- Aroostook County · zone 4a
- Franklin County · zone 4b
- Piscataquis County · zone 4b
3 of 14 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 autumn fern (USDA PHZM 2023):
Zone Comparison
Autumn Fern Needs
- USDA Zones: 6-8
- Sun: Part Sun
- Mature size: 2 ft tall
- Drought tolerance: Low
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 6-8)
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 Autumn Fern 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.
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.
Soil + Drainage Fit
Drainage requirement: poorly (saturated >50% of year). A soil-survey lookup (NRCS SSURGO) flags whether your specific site matches.
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.
What Else to Consider for Autumn Fern 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 autumn fern — is covered on the Maine growing guide.
Where in Maine Autumn Fern Is Zone-Hardy
Autumn Fern is rated for USDA zones 6–8. 2 of Maine’s 16 counties fall inside that band. The coldest that does is Knox County at zone 6a. 14 counties sit below the plant’s zone 6 floor, where an unprotected plant is relying on snow cover and a mild year. Where you are in Maine decides this one.
Across those 16 counties Maine’s winter-low ladder runs from zone 4a in Aroostook County to zone 6a in Lincoln County — 2 USDA zones of spread, which is 20°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.
The planting window moves with it. Piscataquis County holds its last hard freeze (28°F) until about May 15, while Knox County is clear by Apr 4 — 41 days apart. Set autumn fern out on your county’s date, not the state’s.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Autumn Fern’s zone 6–8 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Maine Cooperative Extension
For Maine-specific cultivar recommendations, planting calendars, and pest pressure for autumn fern, 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 Autumn Fern in Maine
When can I plant Autumn Fern 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 Autumn Fern grown in across Maine?
Maine spans USDA hardiness zones 3b-7a (USDA ARS PHZM 2023). Autumn Fern carries a range of zones 6-8, 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). Autumn Fern should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Will Autumn Fern actually grow on my specific land in Maine?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores autumn fern 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 autumn fern against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Maine autumn fern 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 autumn fern average
Explore More
Growing guides for autumn fern
Explore Maine county by county
Maine carries 16 counties with their own USDA zone — a sample of the growing pages for autumn fern there:
Where else autumn fern grows
Autumn Fern'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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