Alfalfa is a cover crop — grown to build and protect the soil rather than for a harvest of its own. It's hardy across USDA zones 2 through 10 and shrugs off dry spells. Its spring flowers are a real draw for honeybees and native bees. A nitrogen-fixer, it draws nitrogen from the air and feeds it back to the soil — turn it under or leave the roots in place, and the next planting inherits a richer bed.
Alfalfa — the short answer
Alfalfa: grown in zones 2–10, full sun, pH 4.3–8.7, about 65 days to maturity.
- USDA zones
- 2–10
- Not verified
- Soil pH
- 4.3–8.7
- FAO ECOCROP
- Sun
- Full Sun
- Converted from FAO ECOCROP
- Days to Maturity
- 65 days
- We haven't confirmed this against a published source yet.
- Frost-kill temp (growing season)
- 32°F
- FAO ECOCROP
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — each tile names its own row's source, because per-field provenance varies.
Score Alfalfa on your exact land.
Zone averages can't see the slope, soil, frost, and sun that decide whether alfalfa actually takes — and those shift from one yard to the next. Enter your address and we'll score alfalfa against your land's real conditions.
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What Alfalfa is
Alfalfa grows as an annual or perennial and reaches around two feet at maturity. It blooms purple in spring.
How to grow Alfalfa
Alfalfa grows in USDA zones 2 through 10. Alfalfa does best in full sun — at least 6 hours of direct sun a day — and soil from pH 4.3 to 8.7, on well-drained ground. It needs around 2,500 growing degree days to mature and a growing season of at least 100 frost-free days, which is why climate matters as much as soil.
USDA Zones
2-10
Not verified
Soil pH
4.3 - 8.7
FAO ECOCROP
Sun
Full Sun
Converted from FAO ECOCROP
Drainage
well (dry spells)
FAO ECOCROP
Frost Kill Temperature
32°F
Where cold starts killing growing tissue. Not a winter-survival floor — a dormant perennial takes far colder, which its hardiness zone answers.
FAO ECOCROP
Minimum Growing Temperature
41°F
Below this it stops growing rather than dies — a pace limit, not a survival limit.
FAO ECOCROP
Days to Maturity
65 days
Alfalfa; perennial nitrogen-fixing cover; deep tap root; multi-year stand.
We haven't confirmed this against a published source yet.
GDD Required
2500+
Growing degree-days of accumulated warmth it needs to mature — humid summers reach this faster than cool coastal ones.
We haven't confirmed this against a published source yet.
Mature Height
2 ft
USDA NRCS PLANTS Database
Frost-Free Days
100+
The frost-free stretch it needs start to finish — short-season areas may need an indoor head start.
Growable Ground plant catalog
Start the season right
Plant alfalfa in full sun with at least 6 hours of direct sun, once the soil has warmed and frost risk has passed. We haven't confirmed this against a published source yet.
Match the soil
Alfalfa prefers pH 4.3 to 8.7 (FAO ECOCROP). A quick soil test from your local Extension lab tells you whether to add lime or sulfur to land in band. It fixes its own nitrogen, so skip the high-nitrogen feed and instead dust the seed with a matching rhizobium inoculant at sowing.
Water while it roots in
Water deeply while alfalfa establishes, letting the soil dry between soakings; once its roots are in, it rides out dry spells on its own.
Turn it in before it seeds
Cut alfalfa down or turn it into the soil before it sets seed, while the growth is still green — that's when it returns the most to the ground.
Where Alfalfa thrives
On hardiness alone, alfalfa grows across most of the country — its range (USDA zones 2 through 10) is unusually wide. Zone is only the starting point, though: the soil pH, drainage, and frost dates on your specific land decide how well it actually does.
A USDA zone is a 10°F band of average annual extreme winter minimum, so zones 2–10 spans average winter lows from -50°F to 40°F (USDA PHZM 2023). Across the 50 states and DC, that band covers 47 outright and splits 4 more down the middle — and which side of that line your land sits on changes the answer.
Zones 2–10·Where Alfalfa growsOpen map →
Continental US shown — Alaska and US Pacific territories sit outside the federal map's polygon dataset.
This map is derived from the USDA ARS / PRISM Plant Hardiness Zone Map (2023) and is not the official USDA Plant Hardiness Zone Map.
Where Alfalfa stands, state by state
Alfalfa is rated for zones 2–10 — a cold floor USDA puts at -50 to -40°F. Across the 50 states and DC, 47 sit fully inside that band, the line runs through 4 more, and 0 sit outside it — and inside every split state, the same line runs on at county grain.
Fully inside zones 2–10
47 states
3 of 47 shown
The line runs through
4 states
- Alaska · zones 1a-9a
- California · zones 4b-11a
- Florida · zones 8b-12a
3 of 4 shown
Alfalfa’s band covers part of each of these states — which side of the line your county sits on changes the answer, and each state page draws it.
State zone extents: USDA Plant Hardiness Zone Map (PHZM) 2023. A zone is a 10°F band of average annual extreme minimum temperature, so a state that splits the band contains the boundary — its own page draws the county line, and a parcel report resolves which side your land sits on.
What grows around Alfalfa
Growing guides for alfalfa
In rotation planning, alfalfa counts as a Legume — beds recover best when legume crops don’t follow each other in the same spot year over year. (Growable Ground derivation — crop-rotation group from botanical family)
Good to know
Alfalfa is a standout pollinator plant — high value to bees and other pollinators. We haven't confirmed this against a published source yet.
Your land is one point inside Alfalfa's range
This page resolves to the species. Your state page draws the county line, and a report reads the parcel — the soil pH, drainage, sun, and frost dates on your exact ground, which no species average can see.
See if Alfalfa will thrive on your land
Zone averages are a start. Your soil pH, drainage, sun exposure, and frost dates shape whether alfalfa actually takes. We score it against the mapped and modelled conditions at your address.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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How we know this about Alfalfa
The figures above are cited per row, not per site: the pH band names this plant’s own source column, the three temperature figures each carry their own, and days-to-maturity cites the publication that actually lists it. All of it comes from the Growable Ground Plant Database — a compilation over FAO ECOCROP, USDA PLANTS, and university Extension sources, published openly with per-field provenance.
Grounded inUSDA PLANTS Database
Frequently asked questions
Can I grow Alfalfa in my zone?
Alfalfa grows in USDA hardiness zones 2 through 10. Zone is one factor — soil pH, drainage, and frost dates on your specific parcel also shape whether it takes.
When should you plant Alfalfa?
Most growers plant alfalfa after the last spring frost, once the soil has warmed, leaving enough of the season for its 100-day frost-free need. Your local frost dates set the exact window — a Growable Ground report reads them for your address.
How much sun does Alfalfa need?
Alfalfa needs full sun — a spot that catches at least 6 hours of direct summer sun a day. We haven't confirmed this against a published source yet. In more shade it still grows, but usually gives a smaller, later crop. The catch is that a yard rarely gets even light everywhere — a fence, the house, or one tall tree can quietly take those hours. A Growable Ground report reads the real sun-hours across your land, canopy and buildings included, so you can pick the brightest bed before you plant.
What soil does Alfalfa need?
Alfalfa prefers soil pH 4.3 to 8.7, on well-drained ground (FAO ECOCROP). Your report scores your parcel's mapped soil against that using USDA SSURGO data.
Does Alfalfa attract pollinators?
Yes — alfalfa's flowers are a strong nectar and pollen source for honeybees and native bees. We haven't confirmed this against a published source yet.
Keep exploring Alfalfa
Alfalfa state by state
Every state alfalfa's zone reaches — 40 link straight to that state's alfalfa growing page; the rest open the state's full growing guide.