South Fork, Colorado, sits in USDA hardiness zone 5a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Among the crops suited to this profile: cabbage, cranberry, lavender, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in South Fork, 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 Fork 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 Fork — soil, climate, flood, and parcel records. How we handle your address.
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South Fork — the short answer
South Fork, Colorado: USDA zone 5a, about 126 days between hard freezes, across 2K acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 22
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 25
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~126
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 2K 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 Fork's average, not your lot's — a low corner or a tree line moves it. Against South Fork's 126-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in South Fork
Each reading below is measured for South Fork itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSouth Fork runs about 126 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 Fork 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 Fork is in
South Fork sits in the Southern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at South Fork's own centroid rather than borrowed from Rio Grande County.
What Grows in South Fork
Every plant below cleared South Fork's own zone 5a and its 126-day season. Each card opens that plant's Colorado profile. How we score.
Is it too late to plant in South Fork?
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 24; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 22 (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. 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 Fork
Closest first, within ~10 miles of South Fork. Listing isn't leaking, and distance isn't exposure.
- The Whistle PigUnderground Storage Tanks · 600 ft
- CDOT South ForkUnderground Storage Tanks · 950 ft
- Rainbow ExpressUnderground Storage Tanks · 1400 ft
- Chinook Store & MotelUnderground Storage Tanks · 0.8 mi
- Stone Forest Industries IncUnderground Storage Tanks · 0.9 mi
- Twin Pine Motor SportsUnderground Storage Tanks · 1.3 mi
- Jackson Lumber CoUnderground Storage Tanks · 1.3 mi
- AT&T SOUTH FORKBrownfields · 1.4 mi
- AT&T South Fork RsUnderground Storage Tanks · 1.6 mi
- AT&Twolf Creek Pass RsUnderground Storage Tanks · 2.1 mi
- Rio Grande County Road DepartmentUnderground Storage Tanks · 3.0 mi
- Wolf Creek RanchUnderground Storage Tanks · 4.1 mi
3 more sites are on the record inside the same radius. See them on the map
Measured from South Fork'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 Fork.
Total Sites
15
within ~10 miles of South Fork
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Severity Distribution
within ~10 miles of South Fork
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •A Superfund listing means federally documented contamination. Test soil and water before planting edibles nearby.
Check your specific parcel in South Fork
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 Fork average
Your land is one point inside South Fork
Everything above resolves to South Fork as a whole — one PHZM band and one 28°F frost record, read across 2K 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 Fork Average
South Fork Average
- ●USDA Zones 5a, averaged across South Fork
- ●One soil character for all of South Fork
- ●Frost dates read at South Fork's scale: May 22 to Sep 25
YOUR Parcel
- ✓Your exact zone, not South Fork's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in South Fork
Pull a site-specific report for your exact address in South Fork, Colorado — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that South Fork averages can't show:
We read public map data around South Fork — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the South Fork average
How we know this about South Fork
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 Fork’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 Fork
When does frost risk typically end in South Fork?
The last hard freeze (28°F) in South Fork typically lands around May 22, 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 12.
When is the first frost in South Fork?
The first hard freeze (28°F) in South Fork 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 126 days after the spring freeze cleared.
How long is the growing season in South Fork?
Measured between 28°F hard freezes, South Fork sees about 126 frost-free days — roughly May 22 through Sep 25, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 12 to Sep 11, about 91 days.
Is the soil safe to grow vegetables in South Fork?
The federal record around South Fork is a meaningful one — 15 documented sites, mostly Underground Storage Tanks entries (13), the nearest Underground Storage Tanks record about 0.1 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do gardeners stretch the season in South Fork?
With about 126 frost-free days between hard freezes, South Fork 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 154 to 182 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 22 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at South Fork's scale — its 5a band and its 126-day season. Your yard writes its own version of South Fork'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 Fork’s own scale
6 of the readings below were taken at South Fork's own scale — its own ~126-day season between 28°F freezes, the 1,628 acres it covers and 15 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- South Fork's own USDA hardiness band, zones 5aUSDA PHZM 2023
- South Fork's own 28°F hard-freeze dates, about May 22 and Sep 25 and the ~126-day span between themNOAA 1991–2020 Climate Normals
- 15 documented contamination sites on the federal record near South Fork, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- South Fork's boundary and the 1,628 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~126-day seasonGrowable Ground crop-matching engine
- The ecoregion at South Fork's own centroid, the Southern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so South Fork's 1,628 acres read through its county's SSURGO summaryfrom Rio Grande County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Rio Grande County
- The growing challenges every Colorado grower plans around — written at state scale, so they stay on the state guidefrom Colorado
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Rio Grande County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among South Fork's 1,628 acreswhy one lot differs from the next →
- Which side of South Fork you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,628 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 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 Fork-wide figureread your own land →
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