Knik River, Alaska, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Growers here do well with cabbage, cranberry, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Knik River, 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 Knik River 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 Knik River — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Knik River — the short answer
Knik River, Alaska: USDA zone 5a, about 145 days between hard freezes, across 52K acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 6
- Matanuska-Susitna Borough normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Sep 28
- Matanuska-Susitna Borough normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~145
- Matanuska-Susitna Borough normal — NOAA 1991–2020, nearest to this town
- Town area
- 52K 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 Matanuska-Susitna Borough’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 5a is Knik River's average, not your lot's — a low corner or a tree line moves it. Against Knik River's 145-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Knik River
Each reading below is measured for Knik River itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsKnik River runs about 145 days between hard freezes (read from Matanuska-Susitna Borough, the closest normal to Knik River) — 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
MeasuredKnik River sits in USDA hardiness zone 5a.
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 Knik River
Every plant below cleared Knik River's own zone 5a and its 145-day season. Each card opens that plant's Alaska profile. How we score.
Is it too late to plant in Knik River?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Apr 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 6 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 28 — 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.
What's on the federal record near Knik River
Closest first, within ~10 miles of Knik River. Listing isn't leaking, and distance isn't exposure.
- SA01600218CBCD1 001Nitrate · 2.5 mi
- SA01600202ABAD1 002Nitrate · 3.6 mi
- SA01600202BAAA1 001Nitrate · 3.7 mi
- SA01700235CDDD1 003Nitrate · 3.8 mi
- SA01600209CCAB1 001Nitrate · 4.0 mi
- Eklutna TunnelMining · 4.8 mi
- SA01700226DDBB1 017Nitrate · 4.8 mi
- SA01700234AABB1 005Nitrate · 4.8 mi
- SA01700226DAAD1 004Nitrate · 4.9 mi
- The Green StoreUnderground Storage Tanks · 5.4 mi
- SA01700226AABA1 009Nitrate · 5.4 mi
- SA01700226BCBB1 006Nitrate · 5.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Knik River'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 Knik River.
Total Sites
140
within ~10 miles of Knik River
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Knik River
Severity Distribution
within ~10 miles of Knik River
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Knik River, two things run higher than the national average within ~10 miles of Knik River — Nitrate (84 sites) and Mining (13 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Knik River
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 Knik River average
Your land is one point inside Knik River
Everything above resolves to Knik River as a whole — one PHZM band, read across 52K acres, with hard-freeze dates borrowed from Matanuska-Susitna Borough’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 Knik River Average
Knik River Average
- ●USDA Zones 5a, averaged across Knik River
- ●One soil character for all of Knik River
- ●Frost dates read at Knik River's scale: May 6 to Sep 28
YOUR Parcel
- ✓Your exact zone, not Knik River's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Knik River
Pull a site-specific report for your exact address in Knik River, Alaska — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Knik River averages can't show:
We read public map data around Knik River — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Knik River average
How we know this about Knik River
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 Matanuska-Susitna Borough’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 Knik River
When does frost risk typically end in Knik River?
The last hard freeze (28°F) in Knik River typically lands around May 6, 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 27.
When is the first frost in Knik River?
The first hard freeze (28°F) in Knik River typically arrives around Sep 28, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 14, so the watching starts about Aug 29 — about 145 days after the spring freeze cleared.
How long is the growing season in Knik River?
Measured between 28°F hard freezes, Knik River sees about 145 frost-free days — roughly May 6 through Sep 28, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 27 to Sep 14, about 110 days.
Is the soil safe to grow vegetables in Knik River?
The federal record around Knik River is a meaningful one — 140 documented sites, mostly Nitrate entries (84), the nearest Nitrate record about 2.5 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 Knik River?
With about 145 frost-free days between hard freezes, Knik River 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 173 to 201 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 6 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Knik River's scale — its 5a band and its 145-day season. Your yard writes its own version of Knik River'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 Knik River’s own scale
4 of the readings below were taken at Knik River's own scale — the 52,301 acres it covers and 140 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Knik River's own USDA hardiness band, zones 5aUSDA PHZM 2023
- 140 documented contamination sites on the federal record near Knik River, the closest Nitrate record about 2.5 miles out from the town centreFederal environmental registers
- Knik River's boundary and the 52,301 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~145-day seasonGrowable Ground crop-matching engine
Inherited from a wider read
- The 28°F hard-freeze dates — Knik River has no normal of its own, so its county's is the closest measured readfrom Matanuska-Susitna Borough
- Soil character — no town-scale survey exists, so Knik River's 52,301 acres read through its county's SSURGO summaryfrom Matanuska-Susitna County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Matanuska-Susitna 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 Matanuska-Susitna County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Knik River's 52,301 acreswhy one lot differs from the next →
- Which side of Knik River you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 52,301 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 2.5 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 Knik River-wide figureread your own land →
More in Alaska
Wider growing context
What grows across AlaskaKnik River sits outside our named growing regions, so Alaska as a whole is its closest context here.
Nearby growing guides