The Matanuska–Susitna Valley (Mat-Su) spans USDA hardiness zones 4a-5b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Alaska's farm heartland — the Mat-Su's long June days grow the state fair's giant cabbages on a 4a-5b valley floor whose committed band runs two zones warmer than the borough's glacier-to-Denali average. On paper, cabbage, potato, rhubarb, and kale all suit these conditions — on the ground, soil, sun, and drainage make the final call.
The Matanuska–Susitna Valley (Mat-Su) spans Alaska.
Your yard isn't all of the Matanuska–Susitna Valley (Mat-Su).
The Matanuska–Susitna Valley (Mat-Su) spans USDA zones 4a-5b, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Matanuska–Susitna Valley (Mat-Su) — soil, climate, flood, and parcel records. How we handle your address.
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The Matanuska–Susitna Valley (Mat-Su) — the short answer
The Matanuska–Susitna Valley (Mat-Su): USDA zones 4a-5b, 125–160 frost-free days depending where in it you stand, in Alaska.
- USDA zones
- 4a-5b
- USDA PHZM 2023, aggregated over the footprint
- Shortest season here
- 125 days
- NOAA Regional Climate Centers ACIS, 1991-2020 — Fishhook
- Towns
- 10
- US Census TIGER/Line 2025
- Region type
- Town cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. The season figure is this region's own record, measured across its 10 member towns, not a state or national average.
Hardiness Zone Range
The Matanuska–Susitna Valley (Mat-Su) is not one growing season
One answer for the Matanuska–Susitna Valley (Mat-Su) averages 10 towns whose growing seasons are 35 days apart — from 125 frost-free days in Fishhook to 160 in Butte. That is the same region, measured the same way, in the same years. Which end of it your land sits nearer decides what finishes before the first hard freeze.
The middle half of 10 towns runs 146–159 days, with a median of 156 days — a 35-day span end to end.
Measured across 10 member towns, each carrying its own 28°F normal. NOAA Regional Climate Centers ACIS, 1991-2020. A member with no own record is absent from the range rather than counted as zero — nothing here is interpolated to the region. Your own site sits somewhere inside this range; a parcel report resolves where.
Where the line runs inside the Matanuska–Susitna Valley (Mat-Su)
The middle half of the Matanuska–Susitna Valley (Mat-Su) runs 146–159 frost-free days, and 3 of its 10 towns sit outside that — 2 on the short side, 1 on the long. A regional planting date describes the middle well and the ends poorly, which is worth knowing before you follow one.
Under 146 frost-free days
2 towns
The end of the region that sets the planting calendar — start seed indoors here and the season stretches to meet the crop.
146–159 frost-free days
7 towns
0 of 7 shown
The middle half of the region, and the part a single regional season describes well.
Over 159 frost-free days
1 town
- Butte · 160 days
Long enough for a second succession of a quick crop after the first comes out.
Each town is placed by its OWN 28°F frost-free normal (NOAA Regional Climate Centers ACIS, 1991-2020), the same figure its own guide page publishes. Elevation, slope and cold-air drainage move a site within its town as well — which is the part only your address resolves.
What Grows in the Matanuska–Susitna Valley (Mat-Su)
All 1 of the plants below that publish a season requirement clear even Fishhook’s 125 frost-free days — so on season alone, this grid works at both ends of the region. The 35-day spread still decides how far past this list you can push, and how early you can start.
Plants matched to the Matanuska–Susitna Valley (Mat-Su)'s USDA zones 4a-5b, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Matanuska–Susitna Valley (Mat-Su)
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the Matanuska–Susitna Valley (Mat-Su)’s USDA zones 4a-5b — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground around the Matanuska–Susitna Valley (Mat-Su)
The USDA soil survey maps this ground county by county. These are those records weighted by land area across the county containing the Matanuska–Susitna Valley (Mat-Su) — the ground the Matanuska–Susitna Valley (Mat-Su) sits in, read at the only grain the survey publishes.
In the county containing the Matanuska–Susitna Valley (Mat-Su), the ground is predominantly Spodosols, at 49% of mapped acres, followed by Histosols (21%), Inceptisols (15%) and Entisols (11%). Seven soil orders appear in that record, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Strandline, Spenard, and Kroto.
45% of those acres are well drained, and another 21% very poorly drained, 2% poorly drained. Topsoil pH runs 5.0–5.2 in that county’s own record.
Soil order
Spodosols
Drainage
Well drained
Topsoil pH
5.0–5.2
Hydric soils
39%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Matanuska–Susitna Valley (Mat-Su)
The soil survey reads this ground county by county, and the readings above are the record for the county containing the Matanuska–Susitna Valley (Mat-Su). Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records45% of the mapped acres across the county containing the Matanuska–Susitna Valley (Mat-Su) are well drained — ground that drains quickly. The survey maps this ground county-wide, so it describes the setting the Matanuska–Susitna Valley (Mat-Su) sits in rather than the valley floor alone.
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
From county recordsTopsoil across the county containing the Matanuska–Susitna Valley (Mat-Su) runs pH 5.0–5.2 — acidic in the one record covering it.
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
From county recordsAbout 39% of the ground across the county containing the Matanuska–Susitna Valley (Mat-Su) 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
Safe to Grow Here?
What the federal record shows across the Matanuska–Susitna Valley (Mat-Su) — and how to grow with it.
Across Matanuska-Susitna County, which contains the Matanuska–Susitna Valley (Mat-Su), the federal record holds 999 documented sites, mostly Mining (398), Nitrate (308) and Underground Storage Tanks (202).
That is the containing county's count — this region is a smaller piece of that ground, so it is context, not a reading of any one lot. Open the map outlined to the Matanuska–Susitna Valley (Mat-Su) to see which records sit where you actually grow.
Sources Checked
Summed across the county containing the Matanuska–Susitna Valley (Mat-Su)
A note from Gnorman
What an experienced grower watches for around here
In and around the Matanuska–Susitna Valley (Mat-Su), two things run higher than the national average across the county containing the Matanuska–Susitna Valley (Mat-Su) — Mining (398 sites) and Nitrate (308 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).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Matanuska–Susitna Valley (Mat-Su)
Everything above resolves to the Matanuska–Susitna Valley (Mat-Su) as a whole — a footprint whose own towns record seasons 35 days apart, and hardiness across zones 4a-5b. Your parcel sits at one point in that range, not in the middle of it. 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 region 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 regional average.
Your Lot vs the Matanuska–Susitna Valley (Mat-Su) Average
Matanuska–Susitna Valley (Mat-Su) Average
- ●USDA Zones 4a-5b, averaged across Matanuska–Susitna Valley (Mat-Su)
- ●One soil character for all of Matanuska–Susitna Valley (Mat-Su)
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Matanuska–Susitna Valley (Mat-Su)'s 4a-5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Matanuska–Susitna Valley (Mat-Su)
Pull a site-specific report for your exact address in the Matanuska–Susitna Valley (Mat-Su) — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Matanuska–Susitna Valley (Mat-Su) averages can't show:
We read public map data around The Matanuska–Susitna Valley (Mat-Su) — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Matanuska–Susitna Valley (Mat-Su) average
How we know this about the Matanuska–Susitna Valley (Mat-Su)
The boundary: the region's own towns — a footprint finer than any county, because the county average would misread this microclimate. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the towns inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Matanuska–Susitna Valley (Mat-Su)
What hardiness zone is the Matanuska–Susitna Valley (Mat-Su)?
The Matanuska–Susitna Valley (Mat-Su) spans USDA hardiness zones 4a-5b, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's own towns. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Matanuska–Susitna Valley (Mat-Su)?
Measured between 28°F hard freezes, the Matanuska–Susitna Valley (Mat-Su)'s towns mostly run 146 to 159 frost-free days, median 156 (NOAA Regional Climate Centers ACIS, 1991–2020, over 10 member towns). That 13-day spread is the honest read — no single season describes 10 towns, and each town guide below carries its own.
When does frost risk end in the Matanuska–Susitna Valley (Mat-Su)?
Across the Matanuska–Susitna Valley (Mat-Su), the middle half of member towns see their last 28°F hard freeze between Apr 24 and May 5 (median Apr 28), and their first fall freeze between Sep 28 and Sep 30. Those are hard freezes, not the last light frost: tender transplants wait for about May 19, and elevation decides which end of a 11-day spread you garden in.
What grows well in the Matanuska–Susitna Valley (Mat-Su)?
The Matanuska–Susitna Valley (Mat-Su)'s conditions suit plants such as Cabbage, Potato, Rhubarb, Kale. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Matanuska–Susitna Valley (Mat-Su) defined?
The Matanuska–Susitna Valley (Mat-Su) is a true microclimate — smaller than the county that contains it, with a growing reality of its own. So this page is built from the region's own 10 towns, each carrying its own hardiness zone and frost record, rather than from a county average measured somewhere else.
Which states does the Matanuska–Susitna Valley (Mat-Su) cover?
The Matanuska–Susitna Valley (Mat-Su) spans Alaska. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Southeast Alaska / Inside Passage Panhandle, Interior Alaska / Tanana Valley (Fairbanks), and Kenai Peninsula Coast share at least one state with the Matanuska–Susitna Valley (Mat-Su). Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Matanuska–Susitna Valley (Mat-Su)’s own scale
6 of the readings below were taken at the Matanuska–Susitna Valley (Mat-Su)'s own scale — the zone 4a-5b band across its footprint, a median 156-day season across its 10 towns and 999 documented federal contamination records across its one county, 999 of them in Matanuska-Susitna County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 4a-5b aggregated across all 10 towns in the footprintUSDA PHZM 2023
- The boundary itself — the 10 towns this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 10 towns run 146 to 159 frost-free days, median 156NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 999 documented federal contamination records across its one county, 999 of them in Matanuska-Susitna County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 49% Spodosols, topsoil pH 5.0–5.2, area-weighted across its one mapped countyUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 4a-5bfrom Alaska
What this page can’t tell you
- Which end of the 13-day range your ground sits at — 146 days at one extreme, 159 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Matanuska–Susitna Valley (Mat-Su)
State growing guides
Towns in this region
The county containing this region
Other growing regions across Alaska
Alaska's temperate rainforest inverts the usual Alaska problem: the constraint here isn't cold, it's a lack of summer heat. The Inside Passage panhandle spans USDA zones 5a–8a overall — 7a–8a in the coastal towns where nearly all of its gardening happens (Sitka 8a, Ketchikan 7b) with a 159–240 day frost-free season — longer than much of the mountain West — yet cloudy, cool, extremely wet maritime summers on acidic, boggy Tongass soils mean heat-lovers like tomatoes and corn stall out while cool-season greens, brassicas, potatoes, rhubarb, and berries thrive. This is the mirror image of Alaska's cold-but-sunny Interior and cannot share a page with it.
Interior Alaska grows on a knife-edge no other American garden shares: a continental cold pocket where winters bottom out near -40F and the region spans zone 1b-4a, its inhabited Tanana floor running roughly 1b-2b — among the coldest settled hardiness zones in the country — yet Fairbanks summers deliver up to ~21 hours of daylight. That midnight sun is the trade: cold-hardy, quick-maturing varieties sprint through an ~85-118 day frost-free window (as short as 85 days out toward Delta Junction and Tok). Success here is a distinct discipline built on high tunnels, short-season cultivars, and exploiting long light — nothing about it resembles the maritime panhandle or the milder Mat-Su, and the coarse state page (a flat 3a-4b) cannot express a 1b-4a region whose settled floor sits at the cold end of that band on a ~90-day season.
Cook Inlet's maritime edge — from Homer's 6b banana-belt bluffs to Seward's 7a harbor, ocean-moderated pockets that garden far milder than the peninsula's interior river flats, on committed place records spanning 4b-7a.