Generally — Most Areas
knockout rose (zones 5-11) 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.
Alaska spans zones 1a-9a, 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 knockout rose against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Knockout Rose Needs
- USDA Zones: 5-11
- Sun: Part Sun
- Mature size: 4 ft tall
- Picking window: ~28 days of harvest
- Drought tolerance: Medium
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 5-11)
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Knockout Rose 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.
Winter standing
Alaska runs as cold as USDA zone 1, and no sourced winter-hardiness floor is on record for knockout rose, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether knockout rose is a permanent planting or a replant-every-spring crop for you turns on your own zone within Alaska; check its hardiness range against that before treating it as long-lived ground.
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.
Soil + Drainage Fit
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.
Knockout Rose in Alaska — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 5-11 (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 Knockout Rose 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 knockout rose — is covered on the Alaska growing guide.
Where in Alaska Knockout Rose Is Zone-Hardy
Knockout Rose is rated for USDA zones 5–11. No Alaska county reaches it. Even Yukon-Koyukuk County, the state’s mildest winter at zone 3a-4b, sits below the plant’s zone 5 floor — so in open ground this one needs winter protection here, or a container that comes under cover.
Across those 30 counties Alaska’s winter-low ladder runs from zone 3a-4b in Aleutians East County to zone 3a-4b in Yukon-Koyukuk County — 1.5 USDA zones of spread, which is 15°F between the two counties’ average coldest night of the year. None of that range reaches the band knockout rose needs, so here the statewide answer really is the answer.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. Knockout Rose’s zone 5–11 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Knockout Rose draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, knockout rose can only work that bloom inside Alaska's frost window — roughly 147 days, opening after the last 28°F freeze (Apr 16 - May 15) and closing at the first (Sep 24 - Oct 29), per NOAA Regional Climate Centers ACIS station record, 1991-2020.
Alaska Cooperative Extension
For Alaska-specific cultivar recommendations, planting calendars, and pest pressure for knockout rose, the canonical source is UAF Cooperative Extension Service. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Knockout Rose in Alaska
When can I plant Knockout Rose 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). No sourced winter-hardiness floor is on record for Knockout Rose, so this page does not state whether it overwinters in Alaska 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 Knockout Rose grown in across Alaska?
Alaska spans USDA hardiness zones 1a-9a (USDA ARS PHZM 2023). Knockout Rose carries a range of zones 5-11, 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). Knockout Rose 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 Knockout Rose actually grow on my specific land in Alaska?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores knockout rose 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 knockout rose against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Alaska knockout rose averages can't show:
We read public map data around Alaska — soil, climate, flood, and parcel records. How we handle your address.
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