Kenai Peninsula Borough, in Alaska, sits in USDA hardiness zones 3a-4b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Among the crops suited to this profile: cabbage, cranberry, epazote, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Kenai Peninsula Borough holds more than one microclimate.
Soils and elevations shift across Kenai Peninsula 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 Kenai Peninsula Borough — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Kenai Peninsula Borough — the short answer
Kenai Peninsula Borough, Alaska: USDA zones 3a-4b, about 148 days between hard freezes, across 10.3M acres.
- USDA zones
- 3a-4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 2
- KENAI AIRPORT station, 99 ft — 64 km away, 30 yr record
- First hard freeze (28°F)
- Sep 27
- KENAI AIRPORT station, 99 ft — 64 km away, 30 yr record
- Days between freezes
- ~148
- KENAI AIRPORT station, 99 ft — 64 km away, 30 yr record
- County area
- 10.3M 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 Kenai Peninsula Borough's average, not your lot's — a low corner or a tree line moves it. Against Kenai Peninsula Borough's 148-day season, see what your own ground reads.
Soil in Kenai Peninsula County
Across Kenai Peninsula County, the ground is predominantly Spodosols, where Starichkof, Strandline, and Spenard are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 5.0, very strongly acidic. Rainfall drains through hydrologic group B soils.
Soil order
Spodosols
Drainage
Well drained
Hydric soils
41%
Soil still varies lot by lot — soil types explained.
How the ground varies across Kenai Peninsula Borough
The USDA soil survey maps 52% of Kenai Peninsula Borough as well drained — but another 32% drains differently: 27% very poorly drained, 2% poorly drained.
Starichkof is the most extensive named soil at 8% of mapped acres, then Strandline (8%) and Spenard (7%).
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 Kenai Peninsula Borough
Each reading below is measured for Kenai Peninsula 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 Kenai Peninsula Borough 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 Kenai Peninsula Borough runs about pH 5.0, 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
Wet ground
MeasuredAbout 41% of Kenai Peninsula Borough is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Season length
MeasuredKenai Peninsula Borough runs about 148 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
What Grows in Kenai Peninsula Borough
We scored all 1,086 plants against Kenai Peninsula Borough's own USDA zone 3a-4b and its own 148-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 Kenai Peninsula 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 Apr 4; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 2 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 27 — 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.
Safe to Grow Here?
What the federal record shows across Kenai Peninsula County — and how to grow with it.
We checked the federal record across Kenai Peninsula County — 1,107 documented sites across 7 of the 9 source types we track.
The most significant on record: 7 Superfund sites (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Kenai Peninsula Borough carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Kenai Peninsula Borough
Closest first, across Kenai Peninsula County. Listing isn't leaking, and distance isn't exposure.
- SB00501011CBCC1 004Nitrate · 16.0 mi
- DRIFT RIVER OIL TERMINALBrownfields · 16.6 mi
- Tuxedni BayMining · 20.2 mi
- Unnamed OccurrenceMining · 21.1 mi
- Difficult CreekMining · 24.1 mi
- Johnson RiverMining · 27.4 mi
- JohnsonMining · 27.5 mi
- Double GlacierMining · 29.3 mi
- SC00101434CCAA1 001Nitrate · 31.4 mi
- Laidlaw Transit Inc.Underground Storage Tanks · 31.4 mi
- Mark LemanUnderground Storage Tanks · 31.4 mi
- SC00101434CACD1 002Nitrate · 31.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Kenai Peninsula 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 Kenai Peninsula Borough.
Total Sites
1,107
across Kenai Peninsula County
Risk Level
High
Highest-severity
7 Superfund sites (none NPL-listed)
Sources Checked
across Kenai Peninsula County
Severity Distribution
across Kenai Peninsula County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Kenai Peninsula Borough, two things run higher than the national average across Kenai Peninsula County — Mining (153 sites) and Nitrate (500 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 Kenai Peninsula 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 Kenai Peninsula Borough average
Your land is one point inside Kenai Peninsula Borough
Everything above resolves to Kenai Peninsula Borough as a whole — one PHZM band and one county frost record, read across 10.3M 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 Kenai Peninsula Borough Average
Kenai Peninsula Borough Average
- ●USDA Zones 3a-4b, averaged across Kenai Peninsula Borough
- ●One soil character for all of Kenai Peninsula Borough
- ●Frost dates read at Kenai Peninsula Borough's scale: May 2 to Sep 27
YOUR Parcel
- ✓Your exact zone, not Kenai Peninsula Borough's 3a-4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Kenai Peninsula Borough
Pull a site-specific report for your exact address in Kenai Peninsula Borough, Alaska — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Kenai Peninsula Borough averages can't show:
We read public map data around Kenai Peninsula Borough — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Kenai Peninsula Borough average
How we know this about Kenai Peninsula 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 Kenai Peninsula Borough carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Kenai Peninsula Borough
When does frost risk typically end in Kenai Peninsula Borough?
The last hard freeze (28°F) in Kenai Peninsula Borough typically lands around May 2, 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 May 23.
How long is the growing season in Kenai Peninsula Borough?
Measured between 28°F hard freezes, Kenai Peninsula Borough sees about 148 frost-free days — roughly May 2 through Sep 27, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 23 to Sep 13, about 113 days.
Is the soil safe to grow vegetables in Kenai Peninsula Borough?
The federal record around Kenai Peninsula Borough runs heavier than most — 1,107 documented sites, mostly Nitrate entries (500), the nearest Nitrate record about 16 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do gardeners stretch the season in Kenai Peninsula Borough?
With about 148 frost-free days between hard freezes, Kenai Peninsula 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 176 to 204 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 2 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Kenai Peninsula Borough's scale — its 3a-4b band and its 148-day season. Your yard writes its own version of Kenai Peninsula 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 Kenai Peninsula Borough’s own scale
6 of the readings below were taken at Kenai Peninsula Borough's own scale — its own ~148-day span between 28°F freezes, the 3 most extensive soil series mapped here and 1,107 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Kenai Peninsula Borough's own USDA hardiness band, zones 3a-4bUSDA PHZM 2023
- Kenai Peninsula Borough's own 28°F hard-freeze dates and its ~148-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Kenai Peninsula BoroughUSDA NRCS SSURGO
- 1,107 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 16 miles outFederal environmental registers
- Kenai Peninsula Borough's boundary and the 10,251,286 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 3a-4b and a ~148-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 Kenai Peninsula Borough — the ~148 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 Kenai Peninsula Borough's 10,251,286 acreswhy one lot differs from the next →
- Which of those 1,107 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 Kenai Peninsula Boroughread your own land →