Generally — Most Areas
sweetbay magnolia (zones 5-10) suits most of Maine (3b-7a) — zones 5-7 are in range, and the rest of the state is the exception.
Sweetbay Magnolia in Maine — the short answer
Sweetbay Magnolia in Maine: hardy in zones 5–10, part sun, against a state median of ~182 frost-free days.
- Plant zones
- 5-10
- 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 sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score sweetbay magnolia against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Maine is not one climate
Maine’s winter-low ladder runs across 16 counties, from zone 4 in Aroostook County to zone 6 in Lincoln County. That is 20°F between the two counties’ average coldest night — the difference between sweetbay magnolia overwintering in the ground and coming under cover.
The middle half of 16 counties runs 4.5–5.5 zones, with a median of 5.5 zones — a 2-zone span end to end.
Measured across 16 Maine counties. USDA PHZM 2023, per county. 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
Sweetbay Magnolia is rated for zones 5–10 — 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 5–10
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 sweetbay magnolia (USDA PHZM 2023):
Zone Comparison
Sweetbay Magnolia Needs
- USDA Zones: 5-10
- Frost-Free Days: 160+
- Sun: Part Sun
- Mature size: 35 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 5-10)
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 Sweetbay Magnolia 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.
Winter standing
Maine runs as cold as USDA zone 3, and no sourced winter-hardiness floor is on record for sweetbay magnolia, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether sweetbay magnolia is a permanent planting or a replant-every-spring crop for you turns on your own zone within Maine; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Piscataquis County, not the statewide average.
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 sweetbay magnolia 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
Sweetbay Magnolia wants 160+ frost-free days; a typical Maine site sees ~182 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
Chill hours
Sweetbay Magnolia requires ~300 chill hours (32-45°F dormancy window). Maine typically banks ~2500 chill hours per winter (from PRISM 1991-2020 climate normals), which keeps this plant on track.
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
Sweetbay Magnolia likes near-neutral soil (pH 4.5-6.5). 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 5 and 6.5 — worth knowing before you decide whether a Maine soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Maine site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
SSURGO maps about 27.4% of Maine as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Sweetbay Magnolia has low drought tolerance, so it is the fast-draining end that will cost you — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
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 Sweetbay Magnolia 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
Growing sweetbay magnolia here specifically
Sweetbay Magnolia wilts without steady moisture and rates to zones 5–10; roughly 21.7% of Maine sits on sandy, excessively-drained ground (SSURGO) that sheds water almost as fast as it falls.
Hold moisture for sweetbay magnolia with deep mulch and drip lines, especially on the droughtiest parcels. How to handle it →
What to actually do about these — and the constraints that apply to every Maine grower, not just sweetbay magnolia — is covered on the Maine growing guide.
Timing shifts within Maine
Maine isn't one climate. In Piscataquis County, the last hard freeze (28°F) holds until about May 15 — roughly 23 days later than the recorded state median — so plant sweetbay magnolia to your county's window, not the statewide date.
Sweetbay Magnolia needs about 160 days of frost-free season to complete its cycle. 12 of Maine’s 16 counties give it that outright. The tightest that does is Oxford County at 161 frost-free days — 1 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
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 sweetbay magnolia about 22 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"). Sweetbay Magnolia's 160-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
Sweetbay Magnolia draws native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, sweetbay magnolia 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 sweetbay magnolia, the canonical source is UMaine Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Sweetbay Magnolia native to Maine?
Sweetbay Magnolia is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Maine. It can still earn a place in a Maine garden — the zone comparison above tells you whether it will thrive.
Looking for plants that belong here? The Maine growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Sweetbay Magnolia in Maine
When can I plant Sweetbay Magnolia 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). No sourced winter-hardiness floor is on record for Sweetbay Magnolia, so this page does not state whether it overwinters in Maine and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Sweetbay Magnolia grown in across Maine?
Maine spans USDA hardiness zones 3b-7a (USDA ARS PHZM 2023). Sweetbay Magnolia carries a range of zones 5-10, 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). Sweetbay Magnolia needs 160+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Piscataquis, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Sweetbay Magnolia native to Maine?
Sweetbay Magnolia is native to parts of the Lower 48, but the USDA PLANTS Database (accessed 2026-07-01) does not document a native range in Maine. It can still earn a place in a Maine garden — the zone comparison above tells you whether it will thrive.
How should I amend the soil for Sweetbay Magnolia in Maine?
Sweetbay Magnolia prefers pH 4.5-6.5 and well (dry spells) drainage (Growable Ground Plant Database). 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 Sweetbay Magnolia actually grow on my specific land in Maine?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores sweetbay magnolia 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 sweetbay magnolia against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Maine sweetbay magnolia 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 sweetbay magnolia average
Explore More
Growing guides for sweetbay magnolia
Explore Maine county by county
Maine carries 16 counties with their own USDA zone — a sample of the growing pages for sweetbay magnolia there:
Where else sweetbay magnolia grows
Sweetbay Magnolia'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.
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
Last updated: