San Luis, Colorado, sits in USDA hardiness zone 5b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
The conditions favor cabbage, cranberry, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Even in San Luis, 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 San Luis 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 San Luis — soil, climate, flood, and parcel records. How we handle your address.
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San Luis — the short answer
San Luis, Colorado: USDA zone 5b, about 135 days between hard freezes, across 363 acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 17
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~135
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 363 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 San Luis's average, not your lot's — a low corner or a tree line moves it. Against San Luis's 135-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in San Luis
Each reading below is measured for San Luis itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSan Luis 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
MeasuredSan Luis 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 San Luis is in
San Luis sits in the Arizona/New Mexico Plateau — EPA Level III, inside the wider North American Deserts. That is read at San Luis's own centroid rather than borrowed from Costilla County.
What Grows in San Luis
Every plant below cleared San Luis'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 San Luis?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 17 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 29 — 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 San Luis
Closest first, within ~10 miles of San Luis. Listing isn't leaking, and distance isn't exposure.
- Central OilUnderground Storage Tanks · 900 ft
- Zegob StoreUnderground Storage Tanks · 1200 ft
- Centennial School District R1Underground Storage Tanks · 1300 ft
- San Luis TexacoUnderground Storage Tanks · 1600 ft
- San Luis Custom CyclesUnderground Storage Tanks · 2200 ft
- Speedway GarageUnderground Storage Tanks · 2400 ft
- Gus ServiceUnderground Storage Tanks · 0.5 mi
- CC03207222CBANitrate · 3.3 mi
- CB00207212ADCNitrate · 3.7 mi
- Alta Vista GroceryUnderground Storage Tanks · 4.0 mi
- unnamed prospectMining · 5.7 mi
- El Plomo DistrictMining · 5.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from San Luis'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 San Luis.
Total Sites
31
within ~10 miles of San Luis
Risk Level
Elevated
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of San Luis
Severity Distribution
within ~10 miles of San Luis
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around San Luis, Mining runs higher than the national average — 7 sites within ~10 miles of San Luis. 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.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in San Luis
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 San Luis average
Your land is one point inside San Luis
Everything above resolves to San Luis as a whole — one PHZM band and one 28°F frost record, read across 363 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 San Luis Average
San Luis Average
- ●USDA Zones 5b, averaged across San Luis
- ●One soil character for all of San Luis
- ●Frost dates read at San Luis's scale: May 17 to Sep 29
YOUR Parcel
- ✓Your exact zone, not San Luis's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in San Luis
Pull a site-specific report for your exact address in San Luis, Colorado — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that San Luis averages can't show:
We read public map data around San Luis — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the San Luis average
How we know this about San Luis
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 San Luis’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 San Luis
When does frost risk typically end in San Luis?
The last hard freeze (28°F) in San Luis typically lands around May 17, 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 7.
When is the first frost in San Luis?
The first hard freeze (28°F) in San Luis typically arrives around Sep 29, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 15, so the watching starts about Aug 30 — about 135 days after the spring freeze cleared.
How long is the growing season in San Luis?
Measured between 28°F hard freezes, San Luis sees about 135 frost-free days — roughly May 17 through Sep 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 7 to Sep 15, about 100 days.
Is the soil safe to grow vegetables in San Luis?
The federal record around San Luis is a meaningful one — 31 documented sites, mostly Underground Storage Tanks entries (13), the nearest Underground Storage Tanks record about 0.2 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 San Luis?
With about 135 frost-free days between hard freezes, San Luis 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 17 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at San Luis's scale — its 5b band and its 135-day season. Your yard writes its own version of San Luis'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 San Luis’s own scale
6 of the readings below were taken at San Luis's own scale — its own ~135-day season between 28°F freezes, the 363 acres it covers and 31 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- San Luis's own USDA hardiness band, zones 5bUSDA PHZM 2023
- San Luis's own 28°F hard-freeze dates, about May 17 and Sep 29 and the ~135-day span between themNOAA 1991–2020 Climate Normals
- 31 documented contamination sites on the federal record near San Luis, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- San Luis's boundary and the 363 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 San Luis's own centroid, the Arizona/New Mexico PlateauUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so San Luis's 363 acres read through its county's SSURGO summaryfrom Costilla County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Costilla 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 Costilla County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among San Luis's 363 acreswhy one lot differs from the next →
- Which side of San Luis you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 363 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.2 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 San Luis-wide figureread your own land →
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