Yes — Strong Match
alfalfa (zones 2-10) covers every zone Vermont contains (4a-6a), so hardiness is not what limits it anywhere in the state.
Your yard isn't the whole zone.
Vermont spans zones 4a-6a, 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 alfalfa against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Alfalfa Needs
- USDA Zones: 2-10
- Frost-Free Days: 100+
- Sun: Full Sun
- Mature size: 3 ft tall
- Drought tolerance: High
Vermont Has
- USDA Zones: 4a-6a
- Last Hard Freeze (28°F): Apr 27 - May 5
- First Hard Freeze (28°F): Oct 10 - Oct 17
- Annual Rainfall: 34-44 inches
- Common Soils: Glacial till, Clay, Silt loam
Plant Zone Range (zones 2-10)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Alfalfa in Vermont
The frost window
Across Vermont, the last spring hard freeze (28°F) clears between Apr 27 and May 5, and the first fall hard freeze lands between Oct 10 and Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 158-day window you can count on — up to 173 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
Alfalfa is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — Vermont's dates above are the whole calendar for it. That makes the last-freeze date the binding constraint, and a warmer pocket of your own yard is worth more to this crop than it is to a transplanted one.
Winter standing
Vermont runs as cold as USDA zone 4, and no sourced winter-hardiness floor is on record for alfalfa, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether alfalfa is a permanent planting or a replant-every-spring crop for you turns on your own zone within Vermont; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Essex County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. 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 alfalfa survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Alfalfa wants 100+ frost-free days; a typical Vermont site sees ~163 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Alfalfa needs ~2500 GDD (base 50°F) to ripen. The state median runs ~1746 GDD (from PRISM 1991-2020 climate normals), so Vermont's typical season runs short on heat — pick a south-facing site and consider season extension.
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
Alfalfa tolerates a wide pH range (pH 4.3-8.7) — 4.4 units, acid ground through alkaline — so soil acidity is rarely what limits it in Vermont. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. It will grow across that whole span, but it does best between pH 6.5 and 7.5 — worth knowing before you decide whether a Vermont soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Vermont 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 18.5% of Vermont as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Alfalfa tolerates drought well, so wet feet — not dry spells — is its real risk here — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Vermont soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Alfalfa in Vermont — Quick Answer
- Verdict: Yes — Strong Match
- Plant Zones: 2-10 (USDA PLANTS Database)
- State Zones: 4a-6a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 27 - May 5 to Oct 10 - Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 65 days
What Else to Consider for Alfalfa in Vermont
Zone compatibility tells you about winter cold survival — but Vermont growers also need to think about:
Short growing season (100-130 frost-free days)
Rocky soils throughout the Green Mountains
Heavy clay in the Champlain Valley
Growing alfalfa here specifically
Alfalfa needs sharp drainage and sends deep roots hardy to about 41°F; in Vermont, about 18.5% of soils are poorly-drained (SSURGO), and standing water is what actually kills it.
Build alfalfa up on a coarse, free-draining mound so its crown never sit in saturated soil. How to handle it →
What to actually do about these — and the constraints that apply to every Vermont grower, not just alfalfa — is covered on the Vermont growing guide.
Timing shifts within Vermont
Vermont isn't one climate. In Essex County, the last hard freeze (28°F) holds until about May 13 — roughly 11 days later than the recorded state median — so plant alfalfa to your county's window, not the statewide date.
Alfalfa needs about 100 days of frost-free season to complete its cycle. Even Essex County — Vermont’s shortest season at 146 frost-free days — clears that by 46 days, so season length isn’t the constraint anywhere in Vermont. What varies is your own parcel.
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"). Alfalfa's 100-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Where in Vermont Fits Best
Even within Vermont's zones 4a-6a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for alfalfa (USDA PHZM 2023):
Pollinator + Wildlife Value
Alfalfa draws honeybees and native bees (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, alfalfa can only work that bloom inside Vermont's frost window — roughly 163 days, opening after the last 28°F freeze (Apr 27 - May 5) and closing at the first (Oct 10 - Oct 17), per NOAA Regional Climate Centers ACIS, 1991-2020.
Vermont Cooperative Extension
For Vermont-specific cultivar recommendations, planting calendars, and pest pressure for alfalfa, the canonical source is UVM Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Alfalfa native to Vermont?
No — the USDA PLANTS Database lists Alfalfa as introduced rather than native in the Lower 48, so it is not part of Vermont's native flora. It grows here as a garden plant; pairing it with a few Vermont natives keeps local pollinators fed too.
Looking for plants that belong here? The Vermont 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 Alfalfa in Vermont
When can I plant Alfalfa in Vermont?
Vermont's last spring hard freeze (28°F) clears between Apr 27 and May 5, and the first fall hard freeze lands between Oct 10 and Oct 17 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Alfalfa, so this page does not state whether it overwinters in Vermont 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 Alfalfa grown in across Vermont?
Vermont spans USDA hardiness zones 4a-6a (USDA ARS PHZM 2023). Alfalfa carries a range of zones 2-10, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Vermont site have?
A typical Vermont site sees ~163 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Alfalfa needs 100+ 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 Essex, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Alfalfa native to Vermont?
No — the USDA PLANTS Database lists Alfalfa as introduced rather than native in the Lower 48, so it is not part of Vermont's native flora. It grows here as a garden plant; pairing it with a few Vermont natives keeps local pollinators fed too.
How should I amend the soil for Alfalfa in Vermont?
Alfalfa tolerates pH 4.3-8.7 and well (dry spells) drainage (FAO ECOCROP). That is a 4.4-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Vermont site — amend for drainage and organic matter first.
Will Alfalfa actually grow on my specific land in Vermont?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores alfalfa 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 Vermont
State-level data is a sketch. Your Growable Ground report scores alfalfa against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Vermont alfalfa averages can't show:
We read public map data around Vermont — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Vermont alfalfa average
Explore More
Growing guides for alfalfa
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
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