Sugarloaf, Colorado, sits in USDA hardiness zone 5b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
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 Sugarloaf, 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 Sugarloaf 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 Sugarloaf — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Sugarloaf — the short answer
Sugarloaf, Colorado: USDA zone 5b, about 151 days between hard freezes, across 1K acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 8
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~151
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 1K 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 Sugarloaf's average, not your lot's — a low corner or a tree line moves it. Against Sugarloaf's 151-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Sugarloaf
Each reading below is measured for Sugarloaf itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSugarloaf runs about 151 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSugarloaf 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 Sugarloaf is in
Sugarloaf sits in the Southern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Sugarloaf's own centroid rather than borrowed from Boulder County.
What Grows in Sugarloaf
Every plant below cleared Sugarloaf's own zone 5b and its 151-day season. Each card opens that plant's Colorado profile. How we score.
Is it too late to plant in Sugarloaf?
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 10; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 8 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 6 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Sugarloaf
Closest first, within ~10 miles of Sugarloaf. Listing isn't leaking, and distance isn't exposure.
- NederlandMining · 350 ft
- Mystery GroupMining · 350 ft
- SB00107225CBAD SITE 005Nitrate · 400 ft
- SB00107225ACCC SITE 006Nitrate · 1800 ft
- SB00107130BCBC SITE C24Nitrate · 0.9 mi
- UnknownMining · 1.3 mi
- Henry No. 1 & No. 2Mining · 1.4 mi
- Summit ShaftMining · 1.4 mi
- SunriseMining · 1.6 mi
- Gray CopperMining · 1.6 mi
- SB00107131DCBB SITE 012Nitrate · 1.7 mi
- OgallaMining · 1.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Sugarloaf'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 Sugarloaf.
Sources Checked
within ~10 miles of Sugarloaf
Severity Distribution
within ~10 miles of Sugarloaf
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Sugarloaf, two things run higher than the national average within ~10 miles of Sugarloaf — Mining (123 sites) and Superfund (11 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.
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 Sugarloaf
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 Sugarloaf average
Your land is one point inside Sugarloaf
Everything above resolves to Sugarloaf as a whole — one PHZM band and one 28°F frost record, read across 1K 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 Sugarloaf Average
Sugarloaf Average
- ●USDA Zones 5b, averaged across Sugarloaf
- ●One soil character for all of Sugarloaf
- ●Frost dates read at Sugarloaf's scale: May 8 to Oct 6
YOUR Parcel
- ✓Your exact zone, not Sugarloaf's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Sugarloaf
Pull a site-specific report for your exact address in Sugarloaf, Colorado — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Sugarloaf averages can't show:
We read public map data around Sugarloaf — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Sugarloaf average
How we know this about Sugarloaf
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 Sugarloaf’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 Sugarloaf
When does frost risk typically end in Sugarloaf?
The last hard freeze (28°F) in Sugarloaf typically lands around May 8, 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 29.
When is the first frost in Sugarloaf?
The first hard freeze (28°F) in Sugarloaf typically arrives around Oct 6, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 22, so the watching starts about Sep 6 — about 151 days after the spring freeze cleared.
How long is the growing season in Sugarloaf?
Measured between 28°F hard freezes, Sugarloaf sees about 151 frost-free days — roughly May 8 through Oct 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 29 to Sep 22, about 116 days.
Is the soil safe to grow vegetables in Sugarloaf?
The federal record around Sugarloaf runs heavier than most — 607 documented sites, mostly Underground Storage Tanks entries (184), the nearest Mining 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 I protect my plants from frost in Sugarloaf?
From about Sep 6 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 6 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 6. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Sugarloaf's scale — its 5b band and its 151-day season. Your yard writes its own version of Sugarloaf'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 Sugarloaf’s own scale
6 of the readings below were taken at Sugarloaf's own scale — its own ~151-day season between 28°F freezes, the 1,394 acres it covers and 607 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Sugarloaf's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Sugarloaf's own 28°F hard-freeze dates, about May 8 and Oct 6 and the ~151-day span between themNOAA 1991–2020 Climate Normals
- 607 documented contamination sites on the federal record near Sugarloaf, the closest Mining record under a tenth of a mile out from the town centreFederal environmental registers
- Sugarloaf's boundary and the 1,394 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~151-day seasonGrowable Ground crop-matching engine
- The ecoregion at Sugarloaf's own centroid, the Southern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Sugarloaf's 1,394 acres read through its county's SSURGO summaryfrom Boulder County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Boulder 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 Boulder County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Sugarloaf's 1,394 acreswhy one lot differs from the next →
- Which side of Sugarloaf you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,394 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Mining 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 Sugarloaf-wide figureread your own land →
More in Colorado
Growing region
Nearby growing guides