Rockport Colony, Montana, sits in USDA hardiness zone 4b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Reliable performers under these conditions include cabbage, cranberry, cilantro, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Rockport Colony, 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 Rockport Colony 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 Rockport Colony — soil, climate, flood, and parcel records. How we handle your address.
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Rockport Colony — the short answer
Rockport Colony, Montana: USDA zone 4b, about 148 days between hard freezes, across 141 acres of town.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~148
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 141 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 4b is Rockport Colony's average, not your lot's — a low corner or a tree line moves it. Against Rockport Colony's 148-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Rockport Colony
Each reading below is measured for Rockport Colony itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRockport Colony 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
MeasuredRockport Colony sits in USDA hardiness zone 4b.
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 Rockport Colony is in
Rockport Colony sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Rockport Colony's own centroid rather than borrowed from Teton County.
What Grows in Rockport Colony
Every plant below cleared Rockport Colony's own zone 4b and its 148-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Rockport Colony?
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 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 Oct 1 — 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 Rockport Colony
Closest first, within ~10 miles of Rockport Colony. Listing isn't leaking, and distance isn't exposure.
- ROCK PORT COLONYCAFO · 150 ft
- 27N08W13CDD 01Nitrate · 4.3 mi
- 27N06W34DCBC01Nitrate · 5.5 mi
- MALMSTROM AFB T 47Underground Storage Tanks · 6.7 mi
- MALMSTROM AFB T 46Underground Storage Tanks · 7.4 mi
- MALMSTROM AFB T 45Underground Storage Tanks · 7.4 mi
- MALMSTROM AFB S 35Underground Storage Tanks · 7.8 mi
- ROCKPORT COLONY INCUnderground Storage Tanks · 7.8 mi
- WINDY RIDGE FARMSUnderground Storage Tanks · 7.8 mi
- SHEELER & SONS ENTERPRISESUnderground Storage Tanks · 8.2 mi
- MDOT DUPUYER SITEUnderground Storage Tanks · 8.6 mi
- JOHN WHETHAMUnderground Storage Tanks · 8.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Rockport Colony'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 Rockport Colony.
Total Sites
21
within ~10 miles of Rockport Colony
Risk Level
Low
Highest-severity
1 concentrated animal feeding operation
Sources Checked
within ~10 miles of Rockport Colony
Severity Distribution
within ~10 miles of Rockport Colony
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Large animal operations push nitrates and bacteria downstream. Below one, test your water.
Check your specific parcel in Rockport Colony
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 Rockport Colony average
Your land is one point inside Rockport Colony
Everything above resolves to Rockport Colony as a whole — one PHZM band and one 28°F frost record, read across 141 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 Rockport Colony Average
Rockport Colony Average
- ●USDA Zones 4b, averaged across Rockport Colony
- ●One soil character for all of Rockport Colony
- ●Frost dates read at Rockport Colony's scale: May 6 to Oct 1
YOUR Parcel
- ✓Your exact zone, not Rockport Colony's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Rockport Colony
Pull a site-specific report for your exact address in Rockport Colony, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Rockport Colony averages can't show:
We read public map data around Rockport Colony — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Rockport Colony average
How we know this about Rockport Colony
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 Rockport Colony’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 Rockport Colony
When does frost risk typically end in Rockport Colony?
The last hard freeze (28°F) in Rockport Colony 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 Rockport Colony?
The first hard freeze (28°F) in Rockport Colony typically arrives around Oct 1, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 17, so the watching starts about Sep 1 — about 148 days after the spring freeze cleared.
How long is the growing season in Rockport Colony?
Measured between 28°F hard freezes, Rockport Colony sees about 148 frost-free days — roughly May 6 through Oct 1, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 27 to Sep 17, about 113 days.
Is the soil safe to grow vegetables in Rockport Colony?
The federal record around Rockport Colony is light — 21 documented sites across the 9 federal source types we checked, mostly Underground Storage Tanks entries (16), the nearest CAFO record under a tenth of a mile 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 Rockport Colony?
With about 148 frost-free days between hard freezes, Rockport Colony 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 6 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Rockport Colony's scale — its 4b band and its 148-day season. Your yard writes its own version of Rockport Colony'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 Rockport Colony’s own scale
6 of the readings below were taken at Rockport Colony's own scale — its own ~148-day season between 28°F freezes, the 141 acres it covers and 21 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Rockport Colony's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Rockport Colony's own 28°F hard-freeze dates, about May 6 and Oct 1 and the ~148-day span between themNOAA 1991–2020 Climate Normals
- 21 documented contamination sites on the federal record near Rockport Colony, the closest CAFO record under a tenth of a mile out from the town centreFederal environmental registers
- Rockport Colony's boundary and the 141 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~148-day seasonGrowable Ground crop-matching engine
- The ecoregion at Rockport Colony's own centroid, the Northwestern Glaciated PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Rockport Colony's 141 acres read through its county's SSURGO summaryfrom Teton County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Teton 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 Teton County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Rockport Colony's 141 acreswhy one lot differs from the next →
- Which side of Rockport Colony you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 141 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest CAFO 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 Rockport Colony-wide figureread your own land →