South Glastonbury, Montana, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
These conditions suit cabbage, cranberry, lavender, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in South Glastonbury, 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 South Glastonbury 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 South Glastonbury — soil, climate, flood, and parcel records. How we handle your address.
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South Glastonbury — the short answer
South Glastonbury, Montana: USDA zone 5a, about 148 days between hard freezes, across 11K acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 9
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~148
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 11K 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 5a is South Glastonbury's average, not your lot's — a low corner or a tree line moves it. Against South Glastonbury's 148-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in South Glastonbury
Each reading below is measured for South Glastonbury itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSouth Glastonbury 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
Winter hardiness
MeasuredSouth Glastonbury 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
The kind of country South Glastonbury is in
South Glastonbury sits in the Middle Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at South Glastonbury's own centroid rather than borrowed from Park County.
What Grows in South Glastonbury
Every plant below cleared South Glastonbury's own zone 5a and its 148-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in South Glastonbury?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Apr 11; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 9 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 4 — 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 South Glastonbury
Closest first, within ~10 miles of South Glastonbury. Listing isn't leaking, and distance isn't exposure.
- HELMET OF SALVATION SHELTER USTUnderground Storage Tanks · 1.2 mi
- GREEN BARN SHELTERUnderground Storage Tanks · 2.2 mi
- LIBERTY SHELTERUnderground Storage Tanks · 2.2 mi
- 5 BAR 6 RANCHUnderground Storage Tanks · 2.5 mi
- COMMUNITY CONTINUITY INCUnderground Storage Tanks · 2.6 mi
- SOUTH GLASTONBURY CORRAL SITEUnderground Storage Tanks · 2.6 mi
- COMMUNITY RESTORATION INCUnderground Storage Tanks · 2.7 mi
- Marble ClaireMining · 3.4 mi
- Morning StarMining · 3.8 mi
- COMMUNITY CONSERVATION ASSOCIATIONUnderground Storage Tanks · 4.3 mi
- SHELTER INVINCIBLE INCUnderground Storage Tanks · 4.7 mi
- EARTH HOME PROPERTIES LLCUnderground Storage Tanks · 5.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from South Glastonbury'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 South Glastonbury.
Severity Distribution
within ~10 miles of South Glastonbury
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around South Glastonbury, Mining runs higher than the national average — 53 sites within ~10 miles of South Glastonbury. 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.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in South Glastonbury
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 South Glastonbury average
Your land is one point inside South Glastonbury
Everything above resolves to South Glastonbury as a whole — one PHZM band and one 28°F frost record, read across 11K 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 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 South Glastonbury Average
South Glastonbury Average
- ●USDA Zones 5a, averaged across South Glastonbury
- ●One soil character for all of South Glastonbury
- ●Frost dates read at South Glastonbury's scale: May 9 to Oct 4
YOUR Parcel
- ✓Your exact zone, not South Glastonbury's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in South Glastonbury
Pull a site-specific report for your exact address in South Glastonbury, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that South Glastonbury averages can't show:
We read public map data around South Glastonbury — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the South Glastonbury average
How we know this about South Glastonbury
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 South Glastonbury’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 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 South Glastonbury
When does frost risk typically end in South Glastonbury?
The last hard freeze (28°F) in South Glastonbury typically lands around May 9, 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 30.
When is the first frost in South Glastonbury?
The first hard freeze (28°F) in South Glastonbury typically arrives around Oct 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 20, so the watching starts about Sep 4 — about 148 days after the spring freeze cleared.
How long is the growing season in South Glastonbury?
Measured between 28°F hard freezes, South Glastonbury sees about 148 frost-free days — roughly May 9 through Oct 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 30 to Sep 20, about 113 days.
Is the soil safe to grow vegetables in South Glastonbury?
The federal record around South Glastonbury runs heavier than most — 73 documented sites, mostly Mining entries (53), the nearest Underground Storage Tanks record about 1.2 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 South Glastonbury?
With about 148 frost-free days between hard freezes, South Glastonbury 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 9 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at South Glastonbury's scale — its 5a band and its 148-day season. Your yard writes its own version of South Glastonbury'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 South Glastonbury’s own scale
6 of the readings below were taken at South Glastonbury's own scale — its own ~148-day season between 28°F freezes, the 11,195 acres it covers and 73 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- South Glastonbury's own USDA hardiness band, zones 5aUSDA PHZM 2023
- South Glastonbury's own 28°F hard-freeze dates, about May 9 and Oct 4 and the ~148-day span between themNOAA 1991–2020 Climate Normals
- 73 documented contamination sites on the federal record near South Glastonbury, the closest Underground Storage Tanks record about 1.2 miles out from the town centreFederal environmental registers
- South Glastonbury's boundary and the 11,195 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~148-day seasonGrowable Ground crop-matching engine
- The ecoregion at South Glastonbury's own centroid, the Middle RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so South Glastonbury's 11,195 acres read through its county's SSURGO summaryfrom Park County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Park County
- The growing challenges every Montana grower plans around — written at state scale, so they stay on the state guidefrom Montana
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Park County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among South Glastonbury's 11,195 acreswhy one lot differs from the next →
- Which side of South Glastonbury you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 11,195 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 1.2 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 South Glastonbury-wide figureread your own land →
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