North Slope Borough, in Alaska, sits in USDA hardiness zones 3a-4b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Well-matched crops include cabbage, cranberry, epazote, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
North Slope Borough holds more than one microclimate.
Soils and elevations shift across North Slope Borough, so your frost dates and drainage aren't the county average. 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 North Slope Borough — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
North Slope Borough — the short answer
North Slope Borough, Alaska: USDA zones 3a-4b, about 98 days between hard freezes, across 56.8M acres.
- USDA zones
- 3a-4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jun 7
- NUIQSUT AIRPORT station, 37 ft — 127 km away, 22 yr record
- First hard freeze (28°F)
- Sep 13
- NUIQSUT AIRPORT station, 37 ft — 127 km away, 22 yr record
- Days between freezes
- ~98
- NUIQSUT AIRPORT station, 37 ft — 127 km away, 22 yr record
- County area
- 56.8M acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 3a-4b is North Slope Borough's average, not your lot's — a low corner or a tree line moves it. Against North Slope Borough's 98-day season, see what your own ground reads.
Soil in North Slope County
Across North Slope County, the ground is predominantly Gelisols, where Inigok, Nuiqsut, and Teshekpuk are the most extensive named soil series. The soil is generally very poorly drained with a silt loam surface. Topsoil pH runs about 4.8–5.6, strongly acidic. Rainfall drains through hydrologic group D soils.
Soil order
Gelisols
Drainage
Very poorly drained
Hydric soils
65%
Soil still varies lot by lot — soil types explained.
How the ground varies across North Slope Borough
The USDA soil survey maps 43% of North Slope Borough as very poorly drained — but another 41% drains differently: 32% somewhat poorly drained, 7% poorly drained.
Inigok is the most extensive named soil at 1% of mapped acres, then Nuiqsut (0%) and Teshekpuk (0%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in North Slope Borough
Each reading below is measured for North Slope Borough itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across North Slope Borough are very poorly drained, in hydrologic group D — ground that sheds water slowly.
Beds can stay saturated for days after heavy rain, and the roots of most vegetables, berries, and fruit trees suffocate or rot in soil that never drains.
Raised beds or mounded rows lift roots above the wet zone; choose water-tolerant crops for the lowest spots.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across North Slope Borough runs about pH 4.8–5.6, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Season length
MeasuredNorth Slope Borough runs about 98 days between hard freezes — 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
MeasuredNorth Slope Borough sits in USDA hardiness zones 3a-4b.
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 North Slope Borough
We scored all 1,086 plants against North Slope Borough's own USDA zone 3a-4b and its own 98-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Alaska profile.
Is it too late to plant in North Slope Borough?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around May 10; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jun 7 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 13 — 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.
Safe to Grow Here?
What the federal record shows across North Slope County — and how to grow with it.
We checked the federal record across North Slope County — 331 documented sites across 7 of the 9 source types we track.
The most significant on record: 30 Superfund sites (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across North Slope County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near North Slope Borough
Closest first, across North Slope County. Listing isn't leaking, and distance isn't exposure.
- UMIAT AFS SITESuperfund · 33.2 mi
- UMIAT AFS SITEBrownfields · 33.2 mi
- USDOI BLM SAGWON AIRSTRIP DUMPSuperfund · 61.9 mi
- USDOI BLM FISH CREEK #1 LEGACY WELLBrownfields · 70.8 mi
- POWER PLANTBrownfields · 79.9 mi
- NORTH SLOPE BOROUGH PUBLIC WORKSBrownfields · 79.9 mi
- VACUUM BUILDINGBrownfields · 80.0 mi
- USDOI BLM KOGRU RIVER DEWLINE SITESuperfund · 82.3 mi
- Siksikpuk RiverMining · 85.5 mi
- Kurupa River SouthwestMining · 89.1 mi
- Karupa RiverMining · 89.2 mi
- KadyMining · 93.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from North Slope Borough'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 North Slope Borough.
Total Sites
331
across North Slope County
Risk Level
Elevated
Highest-severity
30 Superfund sites (none NPL-listed)
Sources Checked
across North Slope County
Severity Distribution
across North Slope County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around North Slope Borough, two things run higher than the national average across North Slope County — Superfund (30 sites) and Mining (102 sites). That's not a problem with your land — it's information about it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in North Slope Borough
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 North Slope Borough average
Your land is one point inside North Slope Borough
Everything above resolves to North Slope Borough as a whole — one PHZM band and one county frost record, read across 56.8M acres. 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 county 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 county average.
Your Lot vs the North Slope Borough Average
North Slope Borough Average
- ●USDA Zones 3a-4b, averaged across North Slope Borough
- ●One soil character for all of North Slope Borough
- ●Frost dates read at North Slope Borough's scale: Jun 7 to Sep 13
YOUR Parcel
- ✓Your exact zone, not North Slope Borough's 3a-4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in North Slope Borough
Pull a site-specific report for your exact address in North Slope Borough, Alaska — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that North Slope Borough averages can't show:
We read public map data around North Slope Borough — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the North Slope Borough average
How we know this about North Slope Borough
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where North Slope Borough carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about North Slope Borough
When does frost risk typically end in North Slope Borough?
The last hard freeze (28°F) in North Slope Borough typically lands around Jun 7, 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 28.
How long is the growing season in North Slope Borough?
Measured between 28°F hard freezes, North Slope Borough sees about 98 frost-free days — roughly Jun 7 through Sep 13, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 28 to Aug 30, about 63 days.
Is the soil safe to grow vegetables in North Slope Borough?
The federal record around North Slope Borough is a meaningful one — 331 documented sites, mostly Brownfields entries (143), the nearest Superfund record about 33 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do gardeners stretch the season in North Slope Borough?
With about 98 frost-free days between hard freezes, North Slope Borough 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 126 to 154 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the Jun 7 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at North Slope Borough's scale — its 3a-4b band and its 98-day season. Your yard writes its own version of North Slope Borough's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Alaska's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at North Slope Borough’s own scale
6 of the readings below were taken at North Slope Borough's own scale — its own ~98-day span between 28°F freezes, the 3 most extensive soil series mapped here and 331 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- North Slope Borough's own USDA hardiness band, zones 3a-4bUSDA PHZM 2023
- North Slope Borough's own 28°F hard-freeze dates and its ~98-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in North Slope BoroughUSDA NRCS SSURGO
- 331 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Superfund record about 33 miles outFederal environmental registers
- North Slope Borough's boundary and the 56,827,328 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 3a-4b and a ~98-day seasonGrowable Ground crop-matching engine
Inherited from a wider read
- The growing challenges every Alaska grower plans around — written at state scale, so they stay on the state guidefrom Alaska
What this page can’t tell you
- How the season shifts across North Slope Borough — the ~98 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among North Slope Borough's 56,827,328 acreswhy one lot differs from the next →
- Which of those 331 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over North Slope Boroughread your own land →