Circle, Alaska, sits in USDA hardiness zone 1b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Crops well matched to these conditions include cabbage, potato, rhubarb, and kale — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Circle, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Circle lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Circle — soil, climate, flood, and parcel records. How we handle your address.
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Circle — the short answer
Circle, Alaska: USDA zone 1b, about 118 days between hard freezes, across 68K acres of town.
- USDA zone
- 1b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 15
- Yukon-Koyukuk Census Area normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Sep 10
- Yukon-Koyukuk Census Area normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~118
- Yukon-Koyukuk Census Area normal — NOAA 1991–2020, nearest to this town
- Town area
- 68K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are Yukon-Koyukuk Census Area’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 1b is Circle's average, not your lot's — a low corner or a tree line moves it. Against Circle's 118-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Circle
Each reading below is measured for Circle itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsCircle runs about 118 days between hard freezes (read from Yukon-Koyukuk Census Area, the closest normal to Circle) — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredCircle sits in USDA hardiness zone 1b.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
What Grows in Circle
Plants matched to Circle's USDA zones 1b, ordered by how much hardiness margin each has here — the ones with room to spare at both ends of this town's band lead. Each links to its full growing profile.
Is it too late to plant in Circle?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 17; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 15 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 10 — long-season crops need about 90 days of runway, quick greens only 30. In a season this compact, fast finishers and cold-hardy greens do the late work, and garlic tucked in before the freeze repays you next summer.
What's on the federal record near Circle
Closest first, within ~10 miles of Circle. Listing isn't leaking, and distance isn't exposure.
- Yukon Trading PostUnderground Storage Tanks · 4.2 mi
Measured from Circle's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Circle.
Severity Distribution
within ~10 miles of Circle
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
Check your specific parcel in Circle
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Circle average
Your land is one point inside Circle
Everything above resolves to Circle as a whole — one PHZM band, read across 68K acres, with hard-freeze dates borrowed from Yukon-Koyukuk Census Area’s record because no 30-year normal resolves at this town’s own centroid. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at town scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Circle Average
Circle Average
- ●USDA Zones 1b, averaged across Circle
- ●One soil character for all of Circle
- ●Frost dates read at Circle's scale: May 15 to Sep 10
YOUR Parcel
- ✓Your exact zone, not Circle's 1b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Circle
Pull a site-specific report for your exact address in Circle, Alaska — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Circle averages can't show:
We read public map data around Circle — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Circle average
How we know this about Circle
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Yukon-Koyukuk Census Area’s record, because none resolves here; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Circle
When does frost risk typically end in Circle?
The last hard freeze (28°F) in Circle typically lands around May 15, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Jun 5.
When is the first frost in Circle?
The first hard freeze (28°F) in Circle typically arrives around Sep 10, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Aug 27, so the watching starts about Aug 11 — about 118 days after the spring freeze cleared.
How long is the growing season in Circle?
Measured between 28°F hard freezes, Circle sees about 118 frost-free days — roughly May 15 through Sep 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 5 to Aug 27, about 83 days.
Is the soil safe to grow vegetables in Circle?
The federal record around Circle is light — 1 documented site across the 9 federal source types we checked, mostly Underground Storage Tanks entries (1), the nearest Underground Storage Tanks record about 4.2 miles out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do gardeners stretch the season in Circle?
With about 118 frost-free days between hard freezes, Circle rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 146 to 174 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 15 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Circle's scale — its 1b band and its 118-day season. Your yard writes its own version of Circle's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Circle’s own scale
3 of the readings below were taken at Circle's own scale — the 67,834 acres it covers and 1 documented sites around it; 6 are borrowed from a wider read, named and linked below.
Measured here
- Circle's own USDA hardiness band, zones 1bUSDA PHZM 2023
- 1 documented contamination sites on the federal record near Circle, the closest Underground Storage Tanks record about 4.2 miles out from the town centreFederal environmental registers
- Circle's boundary and the 67,834 acres inside itUS Census TIGER/Line 2025
Inherited from a wider read
- The 28°F hard-freeze dates — Circle has no normal of its own, so its county's is the closest measured readfrom Yukon-Koyukuk Census Area
- Soil character — no town-scale survey exists, so Circle's 67,834 acres read through its county's SSURGO summaryfrom Yukon-Koyukuk County
- The candidate plant list — Alaska's curated set, filtered to this zone band and re-ordered by how much margin each has herefrom Alaska
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Yukon-Koyukuk County
- The growing challenges every Alaska grower plans around — written at state scale, so they stay on the state guidefrom Alaska
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Yukon-Koyukuk County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Circle's 67,834 acreswhy one lot differs from the next →
- Which side of Circle you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 67,834 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 4.2 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Circle-wide figureread your own land →