Port Alsworth, Alaska, sits in USDA hardiness zone 4a — a zone band wide enough that plant choice, not possibility, is the interesting question.
The conditions favor cabbage, potato, rhubarb, and kale, among others — though every individual site edits that list with its own soil, sun, and drainage.
Even in Port Alsworth, 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 Port Alsworth 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 Port Alsworth — soil, climate, flood, and parcel records. How we handle your address.
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Port Alsworth — the short answer
Port Alsworth, Alaska: USDA zone 4a, about 135 days between hard freezes, across 14K acres of town.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 13
- Lake and Peninsula Borough normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Sep 25
- Lake and Peninsula Borough normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~135
- Lake and Peninsula Borough normal — NOAA 1991–2020, nearest to this town
- Town area
- 14K 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 Lake and Peninsula Borough’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 4a is Port Alsworth's average, not your lot's — a low corner or a tree line moves it. Against Port Alsworth's 135-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Port Alsworth
Each reading below is measured for Port Alsworth itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsPort Alsworth runs about 135 days between hard freezes (read from Lake and Peninsula Borough, the closest normal to Port Alsworth) — 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
MeasuredPort Alsworth sits in USDA hardiness zone 4a.
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 Port Alsworth
Plants matched to Port Alsworth's USDA zones 4a, 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 Port Alsworth?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Apr 15; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 25 — long-season crops need about 90 days of runway, quick greens only 30. Short seasons reward decisiveness — quick-maturing varieties late, hardy greens under cover, and next year’s garlic in the ground before it closes.
What's on the federal record near Port Alsworth
Closest first, within ~10 miles of Port Alsworth. Listing isn't leaking, and distance isn't exposure.
- Tak IiMining · 6.3 mi
- East Takoka CreekMining · 8.2 mi
- GullMining · 9.7 mi
- Kasna CreekMining · 9.7 mi
- Kasna Creek ProspectMining · 9.9 mi
Measured from Port Alsworth'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 Port Alsworth.
Total Sites
8
within ~10 miles of Port Alsworth
Risk Level
Low
Highest-severity
8 mining sites (prospects, none worked)
Severity Distribution
within ~10 miles of Port Alsworth
Highest-Severity Sites
Know Before You Grow
- •Mine waste leaches heavy metals. Test for lead, arsenic and cadmium before growing food here.
Check your specific parcel in Port Alsworth
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 Port Alsworth average
Your land is one point inside Port Alsworth
Everything above resolves to Port Alsworth as a whole — one PHZM band, read across 14K acres, with hard-freeze dates borrowed from Lake and Peninsula 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 Port Alsworth Average
Port Alsworth Average
- ●USDA Zones 4a, averaged across Port Alsworth
- ●One soil character for all of Port Alsworth
- ●Frost dates read at Port Alsworth's scale: May 13 to Sep 25
YOUR Parcel
- ✓Your exact zone, not Port Alsworth's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Port Alsworth
Pull a site-specific report for your exact address in Port Alsworth, Alaska — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Port Alsworth averages can't show:
We read public map data around Port Alsworth — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Port Alsworth average
How we know this about Port Alsworth
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 Lake and Peninsula 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 Port Alsworth
When does frost risk typically end in Port Alsworth?
The last hard freeze (28°F) in Port Alsworth typically lands around May 13, 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 3.
When is the first frost in Port Alsworth?
The first hard freeze (28°F) in Port Alsworth typically arrives around Sep 25, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 11, so the watching starts about Aug 26 — about 135 days after the spring freeze cleared.
How long is the growing season in Port Alsworth?
Measured between 28°F hard freezes, Port Alsworth sees about 135 frost-free days — roughly May 13 through Sep 25, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 3 to Sep 11, about 100 days.
Is the soil safe to grow vegetables in Port Alsworth?
The federal record around Port Alsworth is light — 8 documented sites across the 9 federal source types we checked, mostly Mining entries (8), the nearest Mining record about 6.3 miles out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do gardeners stretch the season in Port Alsworth?
With about 135 frost-free days between hard freezes, Port Alsworth 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 163 to 191 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 13 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Port Alsworth's scale — its 4a band and its 135-day season. Your yard writes its own version of Port Alsworth'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 Port Alsworth’s own scale
3 of the readings below were taken at Port Alsworth's own scale — the 14,437 acres it covers and 8 documented sites around it; 6 are borrowed from a wider read, named and linked below.
Measured here
- Port Alsworth's own USDA hardiness band, zones 4aUSDA PHZM 2023
- 8 documented contamination sites on the federal record near Port Alsworth, the closest Mining record about 6.3 miles out from the town centreFederal environmental registers
- Port Alsworth's boundary and the 14,437 acres inside itUS Census TIGER/Line 2025
Inherited from a wider read
- The 28°F hard-freeze dates — Port Alsworth has no normal of its own, so its county's is the closest measured readfrom Lake and Peninsula Borough
- Soil character — no town-scale survey exists, so Port Alsworth's 14,437 acres read through its county's SSURGO summaryfrom Lake and Peninsula 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 Lake and Peninsula 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 Lake and Peninsula County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Port Alsworth's 14,437 acreswhy one lot differs from the next →
- Which side of Port Alsworth you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 14,437 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Mining record about 6.3 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 Port Alsworth-wide figureread your own land →
More in Alaska
Wider growing context
What grows across AlaskaPort Alsworth sits outside our named growing regions, so Alaska as a whole is its closest context here.
Nearby growing guides