Koyukuk, Alaska, sits in USDA hardiness zone 2a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Growers here do well with cabbage, potato, rhubarb, and kale — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Koyukuk, 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 Koyukuk 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 Koyukuk — soil, climate, flood, and parcel records. How we handle your address.
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Koyukuk — the short answer
Koyukuk, Alaska: USDA zone 2a, about 118 days between hard freezes, across 4K acres of city.
- USDA zone
- 2a
- 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
- City area
- 4K 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 2a is Koyukuk's average, not your lot's — a low corner or a tree line moves it. Against Koyukuk's 118-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Koyukuk
Each reading below is measured for Koyukuk itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsKoyukuk runs about 118 days between hard freezes (read from Yukon-Koyukuk Census Area, the closest normal to Koyukuk) — 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
MeasuredKoyukuk sits in USDA hardiness zone 2a.
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 Koyukuk
Plants matched to Koyukuk's USDA zones 2a, 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 Koyukuk?
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. When the window is tight, the fall moves are quick ones — baby greens, radishes, and garlic set for next season.
Environmental Check
No contamination sources found near Koyukuk
We checked 9 federal environmental databases and found no recorded contamination sites in this area. A clean starting point for growing.
Your land is one point inside Koyukuk
Everything above resolves to Koyukuk as a whole — one PHZM band, read across 4K acres, with hard-freeze dates borrowed from Yukon-Koyukuk Census Area’s record because no 30-year normal resolves at this city’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 city 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 Koyukuk Average
Koyukuk Average
- ●USDA Zones 2a, averaged across Koyukuk
- ●One soil character for all of Koyukuk
- ●Frost dates read at Koyukuk's scale: May 15 to Sep 10
YOUR Parcel
- ✓Your exact zone, not Koyukuk's 2a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Koyukuk
Pull a site-specific report for your exact address in Koyukuk, Alaska — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Koyukuk averages can't show:
We read public map data around Koyukuk — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Koyukuk average
How we know this about Koyukuk
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’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 city grain anywhere on this page — there is no city-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 Koyukuk
When does frost risk typically end in Koyukuk?
The last hard freeze (28°F) in Koyukuk 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 Koyukuk?
The first hard freeze (28°F) in Koyukuk 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 Koyukuk?
Measured between 28°F hard freezes, Koyukuk 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 Koyukuk?
No database can certify soil, but the federal record here is clean: we checked all 9 federal contamination source types and found no documented sites within the search radii around Koyukuk. That means nothing is on record — not that the land is certified clean — so a one-time soil test is still the way to know your own yard's history.
How do gardeners stretch the season in Koyukuk?
With about 118 frost-free days between hard freezes, Koyukuk 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 Koyukuk's scale — its 2a band and its 118-day season. Your yard writes its own version of Koyukuk'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 Koyukuk’s own scale
2 of the readings below were taken at Koyukuk's own scale — the 3,677 acres it covers; 6 are borrowed from a wider read, named and linked below.
Measured here
- Koyukuk's own USDA hardiness band, zones 2aUSDA PHZM 2023
- Koyukuk's boundary and the 3,677 acres inside itUS Census TIGER/Line 2025
Inherited from a wider read
- The 28°F hard-freeze dates — Koyukuk 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 Koyukuk's 3,677 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 Koyukuk's 3,677 acreswhy one lot differs from the next →
- Which side of Koyukuk you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,677 acresreading your own microclimate →
- How much sun your beds actually get once the trees leaf outmeasuring sun honestly →
- 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 Koyukuk-wide figureread your own land →