Allenspark, Colorado, 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.
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 Allenspark, 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 Allenspark 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 Allenspark — soil, climate, flood, and parcel records. How we handle your address.
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Allenspark — the short answer
Allenspark, Colorado: USDA zone 5b, about 135 days between hard freezes, across 8K acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 28
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~135
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 8K 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 Allenspark's average, not your lot's — a low corner or a tree line moves it. Against Allenspark's 135-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Allenspark
Each reading below is measured for Allenspark itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredAllenspark runs about 135 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
MeasuredAllenspark 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 Allenspark is in
Allenspark sits in the Southern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Allenspark's own centroid rather than borrowed from Boulder County.
What Grows in Allenspark
Every plant below cleared Allenspark's own zone 5b and its 135-day season. Each card opens that plant's Colorado profile. How we score.
Is it too late to plant in Allenspark?
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 18; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 28 — long-season crops need about 90 days of runway, quick greens only 30. Short seasons reward decisiveness — quick-maturing varieties late, hardy greens under cover, and next year’s garlic in the ground before it closes.
What's on the federal record near Allenspark
Closest first, within ~10 miles of Allenspark. Listing isn't leaking, and distance isn't exposure.
- Meeker Park Lodge IncUnderground Storage Tanks · 0.7 mi
- PORE WATER AT 06721500Nitrate · 1.0 mi
- Twin SisterMining · 1.3 mi
- Saint Malo CenterUnderground Storage Tanks · 1.5 mi
- Old TownMining · 2.2 mi
- Allenspark GarageUnderground Storage Tanks · 2.6 mi
- Ferncliff StoreUnderground Storage Tanks · 2.8 mi
- XLN - 8Nitrate · 3.2 mi
- EUGENIA MINESuperfund · 4.2 mi
- SB00207204CDCB SITE C18Nitrate · 5.8 mi
- SB00207204CDCC SITE C17Nitrate · 5.9 mi
- Cheley Colorado CampsUnderground Storage Tanks · 6.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Allenspark'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 Allenspark.
Total Sites
98
within ~10 miles of Allenspark
Risk Level
High
Highest-severity
4 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Allenspark
Severity Distribution
within ~10 miles of Allenspark
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Allenspark, two things run higher than the national average within ~10 miles of Allenspark — Mining (18 sites) and Superfund (4 sites). That's not a problem with your land — it's information about 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 Allenspark
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 Allenspark average
Your land is one point inside Allenspark
Everything above resolves to Allenspark as a whole — one PHZM band and one 28°F frost record, read across 8K 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 Allenspark Average
Allenspark Average
- ●USDA Zones 5b, averaged across Allenspark
- ●One soil character for all of Allenspark
- ●Frost dates read at Allenspark's scale: May 16 to Sep 28
YOUR Parcel
- ✓Your exact zone, not Allenspark's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Allenspark
Pull a site-specific report for your exact address in Allenspark, Colorado — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Allenspark averages can't show:
We read public map data around Allenspark — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Allenspark average
How we know this about Allenspark
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 Allenspark’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 Allenspark
When does frost risk typically end in Allenspark?
The last hard freeze (28°F) in Allenspark typically lands around May 16, 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 6.
When is the first frost in Allenspark?
The first hard freeze (28°F) in Allenspark typically arrives around Sep 28, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 14, so the watching starts about Aug 29 — about 135 days after the spring freeze cleared.
How long is the growing season in Allenspark?
Measured between 28°F hard freezes, Allenspark sees about 135 frost-free days — roughly May 16 through Sep 28, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 6 to Sep 14, about 100 days.
Is the soil safe to grow vegetables in Allenspark?
The federal record around Allenspark runs heavier than most — 98 documented sites, mostly Underground Storage Tanks entries (37), the nearest Underground Storage Tanks record about 0.7 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 Allenspark?
With about 135 frost-free days between hard freezes, Allenspark 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 163 to 191 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 16 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Allenspark's scale — its 5b band and its 135-day season. Your yard writes its own version of Allenspark'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 Allenspark’s own scale
6 of the readings below were taken at Allenspark's own scale — its own ~135-day season between 28°F freezes, the 7,640 acres it covers and 98 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Allenspark's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Allenspark's own 28°F hard-freeze dates, about May 16 and Sep 28 and the ~135-day span between themNOAA 1991–2020 Climate Normals
- 98 documented contamination sites on the federal record near Allenspark, the closest Underground Storage Tanks record about 0.7 miles out from the town centreFederal environmental registers
- Allenspark's boundary and the 7,640 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~135-day seasonGrowable Ground crop-matching engine
- The ecoregion at Allenspark's own centroid, the Southern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Allenspark's 7,640 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 Allenspark's 7,640 acreswhy one lot differs from the next →
- Which side of Allenspark you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 7,640 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.7 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 Allenspark-wide figureread your own land →
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