Generally — Most Areas
Wimmera ryegrass (zones 5-10) suits most of Alaska (1a-9a) — zones 5-9 are in range, and the rest of the state is the exception.
Your yard isn't the whole zone.
Wimmera Ryegrass is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Alaska site runs ~147 frost-free days, but that is a state median, not your yard: slope, trees, and low spots move the last-frost date across a single parcel. Enter your address and we'll score wimmera ryegrass against your land's actual frost dates, sun, and soil.
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Zone Comparison
Wimmera Ryegrass Needs
- USDA Zones: 5-10
- Frost-Free Days: 70+
- Sun: Full Sun
- Drought tolerance: Low
Alaska Has
- USDA Zones: 1a-9a
- Last Hard Freeze (28°F): Apr 16 - May 15
- First Hard Freeze (28°F): Sep 24 - Oct 29
- Annual Rainfall: 10-160 inches
- Common Soils: Permafrost, Glacial silt, Volcanic ash
Plant Zone Range (zones 5-10)
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 Wimmera Ryegrass in Alaska
The frost window
Across Alaska, the last spring hard freeze (28°F) clears between Apr 16 and May 15, and the first fall hard freeze lands between Sep 24 and Oct 29 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 132-day window you can count on — up to 196 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 tenderness
Wimmera Ryegrass is frost-tender — its listed minimum temperature is 41°F (USDA PLANTS Database) — so set plants out two to three weeks PAST your local last hard freeze, not on it and not on the state's earliest date. The 28°F marker above is when killing freezes stop, not when light frost does.
When to start the seed
Wimmera Ryegrass is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — Alaska'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.
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 wimmera ryegrass survives winter in part of Alaska, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Wimmera Ryegrass wants 70+ frost-free days; a typical Alaska site sees ~147 (NOAA Regional Climate Centers ACIS station record, 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 station record, 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
Wimmera Ryegrass likes near-neutral soil (pH 6-8). That's the common-ground band across Alaska's permafrost and glacial silt — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6.5 and 7 — worth knowing before you decide whether a Alaska soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Alaska site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH and drainage requirements from USDA PLANTS Database. Alaska soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Wimmera Ryegrass in Alaska — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 5-10 (USDA PLANTS Database)
- State Zones: 1a-9a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 16 - May 15 to Sep 24 - Oct 29 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Wimmera Ryegrass in Alaska
Zone compatibility tells you about winter cold survival — but Alaska growers also need to think about:
Extremely short growing season (70-110 frost-free days)
Permafrost prevents deep root growth in many areas
Limited soil development in glacial terrain
What to actually do about these — and the constraints that apply to every Alaska grower, not just wimmera ryegrass — is covered on the Alaska growing guide.
Timing shifts within Alaska
Wimmera Ryegrass needs about 70 days of frost-free season to complete its cycle. Even Southeast Fairbanks County — Alaska’s shortest season at 85 frost-free days — clears that by 15 days, so season length isn’t the constraint anywhere in Alaska. What varies is your own parcel.
Across Alaska’s 28 counties the frost-free season runs from 85 days in Southeast Fairbanks County to 240 days in Sitka County — a spread of 155 days, which is why a single statewide planting date misleads. The median Alaska county sees 147 frost-free days, leaving wimmera ryegrass about 77 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"). Wimmera Ryegrass's 70-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Alaska Cooperative Extension
For Alaska-specific cultivar recommendations, planting calendars, and pest pressure for wimmera ryegrass, the canonical source is UAF Cooperative Extension Service. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Wimmera Ryegrass native to Alaska?
No — the USDA PLANTS Database lists Wimmera Ryegrass as introduced rather than native in the Lower 48, so it is not part of Alaska's native flora. It grows here as a garden plant; pairing it with a few Alaska natives keeps local pollinators fed too.
Looking for plants that belong here? The Alaska 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 Wimmera Ryegrass in Alaska
When can I plant Wimmera Ryegrass in Alaska?
Alaska's last spring hard freeze (28°F) clears between Apr 16 and May 15, and the first fall hard freeze lands between Sep 24 and Oct 29 (NOAA Regional Climate Centers ACIS, 1991-2020). Wimmera Ryegrass is frost-tender — its listed minimum temperature is 41°F (USDA PLANTS Database) — so wait two to three weeks past your site's last hard freeze, when light frost has also stopped, before planting out.
What hardiness zone is Wimmera Ryegrass grown in across Alaska?
Alaska spans USDA hardiness zones 1a-9a (USDA ARS PHZM 2023). Wimmera Ryegrass 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 Alaska site have?
A typical Alaska site sees ~147 frost-free days per year (derived from NOAA Regional Climate Centers ACIS station record, 1991-2020). Wimmera Ryegrass needs 70+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Wimmera Ryegrass native to Alaska?
No — the USDA PLANTS Database lists Wimmera Ryegrass as introduced rather than native in the Lower 48, so it is not part of Alaska's native flora. It grows here as a garden plant; pairing it with a few Alaska natives keeps local pollinators fed too.
How should I amend the soil for Wimmera Ryegrass in Alaska?
Wimmera Ryegrass prefers pH 6-8 and well (dry spells) drainage (FAO ECOCROP). That sits in the common-ground band across Alaska soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Wimmera Ryegrass actually grow on my specific land in Alaska?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores wimmera ryegrass 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 Alaska
State-level data is a sketch. Your Growable Ground report scores wimmera ryegrass against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Alaska wimmera ryegrass averages can't show:
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