Mackay, Idaho, sits in USDA hardiness zone 5b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Crops well matched to these conditions include cabbage, cranberry, lavender, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Mackay, 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 Mackay 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 Mackay — soil, climate, flood, and parcel records. How we handle your address.
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Mackay — the short answer
Mackay, Idaho: USDA zone 5b, about 122 days between hard freezes, across 554 acres of city.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 24
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~122
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 554 acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 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 5b is Mackay's average, not your lot's — a low corner or a tree line moves it. Against Mackay's 122-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Mackay
Each reading below is measured for Mackay itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredMackay runs about 122 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
Winter hardiness
MeasuredMackay sits in USDA hardiness zone 5b.
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
The kind of country Mackay is in
Mackay sits in the Middle Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Mackay's own centroid, and it is not what its county reads: Custer County is mostly Idaho Batholith. The wider page above you is answering a different question about different ground.
What Grows in Mackay
Every plant below cleared Mackay's own zone 5b and its 122-day season. Each card opens that plant's Idaho profile. How we score.
Is it too late to plant in Mackay?
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 26; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 24 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 23 — long-season crops need about 90 days of runway, quick greens only 30. Even here the calendar’s edges hold value: thirty-day greens late in the window, then garlic and a rested bed for spring.
What's on the federal record near Mackay
Closest first, within ~10 miles of Mackay. Listing isn't leaking, and distance isn't exposure.
- LOST RIVER ELECTRIC COOPUnderground Storage Tanks · 500 ft
- CHALLIS NATIONAL FORESTUnderground Storage Tanks · 800 ft
- Oasis Stop N Go #24Underground Storage Tanks · 850 ft
- SAMMYS MINI MARTUnderground Storage Tanks · 850 ft
- WALL INCUnderground Storage Tanks · 950 ft
- MAC'S MINI MARTUnderground Storage Tanks · 1000 ft
- USDA FS SALMON CHALLIS NF: OLD MACKAY WAREHOUSESuperfund · 1100 ft
- LOST RIVER HIGHWAY DISTUnderground Storage Tanks · 1500 ft
- Mackay School District #182Underground Storage Tanks · 1700 ft
- Mackay Area Lead-Zinc-CopperMining · 2400 ft
- 07N 24E 28CDD1Nitrate · 0.7 mi
- 07N 24E 34ACA1Nitrate · 1.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Mackay'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 Mackay.
Total Sites
54
within ~10 miles of Mackay
Risk Level
High
Highest-severity
3 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Mackay
Severity Distribution
within ~10 miles of Mackay
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Mackay, two things run higher than the national average within ~10 miles of Mackay — Mining (28 sites) and Superfund (3 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Mackay
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 Mackay average
Your land is one point inside Mackay
Everything above resolves to Mackay as a whole — one PHZM band and one 28°F frost record, read across 554 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 city 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 Mackay Average
Mackay Average
- ●USDA Zones 5b, averaged across Mackay
- ●One soil character for all of Mackay
- ●Frost dates read at Mackay's scale: May 24 to Sep 23
YOUR Parcel
- ✓Your exact zone, not Mackay's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Mackay
Pull a site-specific report for your exact address in Mackay, Idaho — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Mackay averages can't show:
We read public map data around Mackay — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Mackay average
How we know this about Mackay
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Mackay’s own record; 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 city grain anywhere on this page — there is no city-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 Mackay
When does frost risk typically end in Mackay?
The last hard freeze (28°F) in Mackay typically lands around May 24, 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 14.
When is the first frost in Mackay?
The first hard freeze (28°F) in Mackay typically arrives around Sep 23, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 9, so the watching starts about Aug 24 — about 122 days after the spring freeze cleared.
How long is the growing season in Mackay?
Measured between 28°F hard freezes, Mackay sees about 122 frost-free days — roughly May 24 through Sep 23, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 14 to Sep 9, about 87 days.
Is the soil safe to grow vegetables in Mackay?
The federal record around Mackay runs heavier than most — 54 documented sites, mostly Mining entries (28), the nearest Underground Storage Tanks record under a tenth of a mile 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 Mackay?
With about 122 frost-free days between hard freezes, Mackay 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 150 to 178 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 24 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Mackay's scale — its 5b band and its 122-day season. Your yard writes its own version of Mackay'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 Mackay’s own scale
6 of the readings below were taken at Mackay's own scale — its own ~122-day season between 28°F freezes, the 554 acres it covers and 54 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Mackay's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Mackay's own 28°F hard-freeze dates, about May 24 and Sep 23 and the ~122-day span between themNOAA 1991–2020 Climate Normals
- 54 documented contamination sites on the federal record near Mackay, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Mackay's boundary and the 554 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~122-day seasonGrowable Ground crop-matching engine
- Mackay sits in the Middle Rockies — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Mackay's 554 acres read through its county's SSURGO summaryfrom Custer County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Custer County
- The growing challenges every Idaho grower plans around — written at state scale, so they stay on the state guidefrom Idaho
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Custer County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Mackay's 554 acreswhy one lot differs from the next →
- Which side of Mackay you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 554 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile 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 Mackay-wide figureread your own land →
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