Kusilvak Census Area, in Alaska, sits in USDA hardiness zones 3a-4b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
A short list that earns its place here — cabbage, chokecherry, roman chamomile, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring
Kusilvak Census Area holds more than one microclimate.
Soils and elevations shift across Kusilvak Census Area, 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 Kusilvak Census Area — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Kusilvak Census Area — the short answer
Kusilvak Census Area, Alaska: USDA zones 3a-4b, across 11.0M acres.
- USDA zones
- 3a-4b
- USDA PHZM 2023
- Last hard freeze (statewide)
- Apr 16 - May 15
- NOAA RCC ACIS 1991–2020, state middle half
- First hard freeze (statewide)
- Sep 24 - Oct 29
- NOAA RCC ACIS 1991–2020, state middle half
- County area
- 11.0M acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Where no local normal resolves, the figure is the statewide middle-half window, labelled as such rather than passed off as local.
Hardiness Zone Range
Growing Season
Zone 3a-4b is Kusilvak Census Area's average, not your lot's — a low corner or a tree line moves it. Against that, see what your own ground reads.
Soil in Kusilvak County
Across Kusilvak County, the ground is predominantly Inceptisols, where Nulatohills, Paugna, and Mountmcdonald are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 4.3–5.6, very strongly acidic. Rainfall drains through hydrologic group B soils.
Soil order
Inceptisols
Drainage
Well drained
Hydric soils
9%
Soil still varies lot by lot — soil types explained.
How the ground varies across Kusilvak Census Area
The USDA soil survey maps 76% of Kusilvak Census Area as well drained — but another 24% drains differently: 19% moderately well drained, 4% poorly drained.
Nulatohills is the most extensive named soil at 23% of mapped acres, then Paugna (10%) and Mountmcdonald (9%).
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 Kusilvak Census Area
Each reading below is measured for Kusilvak Census Area itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Kusilvak Census Area are well drained, in hydrologic group B — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Kusilvak Census Area runs about pH 4.3–5.6, 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
Winter hardiness
MeasuredKusilvak Census Area 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 Kusilvak Census Area
We scored all 1,086 plants against Kusilvak Census Area's own USDA zone 3a-4b, 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.
Safe to Grow Here?
What the federal record shows across Kusilvak County — and how to grow with it.
We checked the federal record across Kusilvak County — 40 documented sites across 5 of the 9 source types we track.
The most significant on record: 2 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 Kusilvak 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 Kusilvak Census Area
Closest first, across Kusilvak County. Listing isn't leaking, and distance isn't exposure.
- USDOT FAA SAINT MARYS AIR NAV STASuperfund · 15.5 mi
- DOT&PF SAINT MARYS AIRPORTBrownfields · 15.9 mi
- ADOTPF - Saint MarysUnderground Storage Tanks · 16.8 mi
- ST Mary's AirportUnderground Storage Tanks · 16.8 mi
- SB02107027DBDD1 001Nitrate · 45.2 mi
- ArnoldMining · 52.0 mi
- Arnold Gold-Silver ProspectMining · 52.0 mi
- SB03008115DABD1 001Nitrate · 54.1 mi
- EMMONAK CY OFBrownfields · 54.3 mi
- Wolf Creek MountainMining · 54.4 mi
- ALAKANUK SCHOOL - LYSDBrownfields · 54.5 mi
- SB02808410BCAD1 001Nitrate · 55.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Kusilvak Census Area'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 Kusilvak Census Area.
Total Sites
40
across Kusilvak County
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
across Kusilvak County
Severity Distribution
across Kusilvak County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Kusilvak Census Area, two things run higher than the national average across Kusilvak County — Mining (13 sites) and Nitrate (18 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Kusilvak Census Area
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 Kusilvak Census Area average
Your land is one point inside Kusilvak Census Area
Everything above resolves to Kusilvak Census Area as a whole — one PHZM band and one county frost record, read across 11.0M 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 Kusilvak Census Area Average
Kusilvak Census Area Average
- ●USDA Zones 3a-4b, averaged across Kusilvak Census Area
- ●One soil character for all of Kusilvak Census Area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Kusilvak Census Area's 3a-4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Kusilvak Census Area
Pull a site-specific report for your exact address in Kusilvak Census Area, Alaska — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Kusilvak Census Area averages can't show:
We read public map data around Kusilvak Census Area — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Kusilvak Census Area average
How we know this about Kusilvak Census Area
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 Kusilvak Census Area carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Kusilvak Census Area
When does frost risk typically end in Kusilvak Census Area?
Kusilvak Census Area has no hard-freeze normal of its own, so it follows Alaska's statewide window: the middle half of counties see their last spring hard freeze (28°F) around Apr 16 - May 15 and their first fall hard freeze around Sep 24 - Oct 29, per NOAA Regional Climate Centers ACIS (1991–2020). Frost dates shift with elevation and local microclimate, so watch your own site's cold pockets. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
Is the soil safe to grow vegetables in Kusilvak Census Area?
The federal record around Kusilvak Census Area is a meaningful one — 40 documented sites, mostly Nitrate entries (18), the nearest Superfund record about 16 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.
Everything above is measured at Kusilvak Census Area's scale — its 3a-4b band and its zone 3a-4b. Your yard writes its own version of Kusilvak Census Area'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 Kusilvak Census Area’s own scale
5 of the readings below were taken at Kusilvak Census Area's own scale — the 3 most extensive soil series mapped here and 40 documented sites inside its boundary; 2 are borrowed from a wider read, named and linked below.
Measured here
- Kusilvak Census Area's own USDA hardiness band, zones 3a-4bUSDA PHZM 2023
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Kusilvak Census AreaUSDA NRCS SSURGO
- 40 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Superfund record about 16 miles outFederal environmental registers
- Kusilvak Census Area's boundary and the 10,976,930 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear Kusilvak Census Area's hardiness zoneGrowable Ground crop-matching engine
Inherited from a wider read
What this page can’t tell you
- How the season shifts from one end of Kusilvak Census Area to the other — town normals split the differencetowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Kusilvak Census Area's 10,976,930 acreswhy one lot differs from the next →
- Which of those 40 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 Kusilvak Census Arearead your own land →