Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 81152 — San Luis, CO

ZIP code 81152 (San Luis, Costilla County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 31 and the first fall frost September 23.

Where ZIP 81152 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostMay 31
First frostSep 23
2012 zone5b

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for San Luis, CO…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in San Luis, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 31median — 50% chance of a later frost
Safe for tender plantsJune 14only 10% chance of frost after
First fall frostSeptember 23median — 10% chance by Sep 10
Growing season115 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 13 and returns around September 30.

From the NOAA station San Luis 1 S, CO — 4 miles away, elevation 7,943 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 81152

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 19 – May 3
SpinachSow outdoors · Apr 19 – May 10
Broccoli, cabbageStart indoors · Mar 22 – Apr 5
Broccoli, cabbageTransplant · May 10 – May 24
Onion setsPlant outdoors · May 3 – May 17
PotatoesPlant outdoors · May 10 – May 24
LettuceSow outdoors · May 3 – May 17
Carrots, beetsSow outdoors · May 10 – May 24
TomatoesStart indoors · Apr 5 – Apr 19
TomatoesTransplant · Jun 7 – Jun 21
Peppers, eggplantStart indoors · Mar 22 – Apr 5
Peppers, eggplantTransplant · Jun 14 – Jun 28
BeansSow outdoors · Jun 7 – Jun 21
Sweet cornSow outdoors · Jun 7 – Jun 21
Cucumbers, squashSow outdoors · Jun 7 – Jun 21
Fall lettuce, spinachSow outdoors · Jul 29 – Aug 12
GarlicPlant cloves · Sep 9 – Oct 14
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 31) and first fall frost (Sep 23) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 81152 came on Mar 23 — 25 days earlier than the 1991–2020 average (Apr 17).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 5b in Colorado

546 plants native to the lower 48 states, recorded in Colorado, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 27

American elm120 ft · blooms early spring · medium shade tolerance · to −46 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fblack walnut100 ft · blooms late spring · high shade tolerance · to −28 °Fblack willow100 ft · blooms early spring · high shade tolerance · to −58 °Fblue spruce100 ft · blooms late spring · medium shade tolerance · to −38 °F

Shrubs 98

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FApache plume6 ft · blooms late spring · high shade tolerance · to −23 °F

Wildflowers & perennials 246

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine aster0.3 ft · blooms early summer · medium shade tolerance · to −28 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °F

Grasses 163

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °F

Vines 3

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °Fwestern white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in San Luis, CO.

Soil in San Luis, CO

The soil mapped at the center of ZIP 81152 is Eastdale — loam, poorly drained.

TextureLoama good balance for most vegetables
pH8.0alkaline; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter5%high
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Eastdale loam, 0 to 1 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 81152; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in San Luis, CO

Summer high82 °Faverage high, July
Winter low6 °Faverage low, January
Hot days2days a year at 90 °F or more
Freezing nights211nights a year at 32 °F or less
Growing degree days1,542base 50 °F — the season’s usable heat
Longest day14 h 43 mindaylight on June 21
Shortest day9 h 36 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation9 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 37 °F, low 6 °F 37°6° JanFebruary: average high 41 °F, low 12 °F 41°12° FebMarch: average high 52 °F, low 23 °F 52°23° MarApril: average high 58 °F, low 27 °F 58°27° AprMay: average high 68 °F, low 35 °F 68°35° MayJune: average high 79 °F, low 42 °F 79°42° JunJuly: average high 82 °F, low 48 °F 82°48° JulAugust: average high 79 °F, low 47 °F 79°47° AugSeptember: average high 74 °F, low 39 °F 74°39° SepOctober: average high 63 °F, low 28 °F 63°28° OctNovember: average high 49 °F, low 18 °F 49°18° NovDecember: average high 39 °F, low 9 °F 39°9° Dec

Precipitation by month inches

0″1″2″January: 0.38 in precipitation 0.4 JanFebruary: 0.50 in precipitation 0.5 FebMarch: 0.35 in precipitation 0.3 MarApril: 0.56 in precipitation 0.6 AprMay: 0.73 in precipitation 0.7 MayJune: 0.79 in precipitation 0.8 JunJuly: 1.51 in precipitation 1.5 JulAugust: 1.29 in precipitation 1.3 AugSeptember: 1.04 in precipitation 1.0 SepOctober: 0.94 in precipitation 0.9 OctNovember: 0.50 in precipitation 0.5 NovDecember: 0.41 in precipitation 0.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: San Luis 1 S, CO (4 mi away); precipitation: San Luis 1 S, CO (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

6 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

811265b
Chama, CO · 3 mi
875245a
Costilla, NM · 14 mi
875126a
Amalia, NM · 15 mi
811385a
Jaroso, CO · 15 mi
811515a
Sanford, CO · 19 mi
811235a
Blanca, CO · 21 mi
811335b
Fort Garland, CO · 22 mi
810556a
La Veta, CO · 23 mi

Colorado planting zones →

Questions about 81152

What planting zone is ZIP code 81152?

ZIP code 81152 (San Luis, CO) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in San Luis, CO?

The median last spring frost (32 °F) near 81152 is May 31; after June 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, San Luis 1 S station.

When is the first frost in San Luis, CO?

The median first fall frost near 81152 is September 23, giving a median frost-free growing season of 115 days.

When should I plant tomatoes in 81152?

Start tomato seeds indoors around Apr 5 – Apr 19 and set transplants outside around Jun 7 – Jun 21, one to three weeks after the median last frost.

How much rain and snow does 81152 get?

About 9 inches of precipitation a year (NOAA 1991–2020 normals, San Luis 1 S station).

How hot do summers get in San Luis, CO?

The average high peaks at 82 °F in July, with about 2 days a year at 90 °F or more.

What kind of soil does 81152 have?

The USDA soil survey maps Eastdale at the center of ZIP 81152: loam, poorly drained, pH about 8.0 (alkaline).

Did spring come early in San Luis, CO in 2026?

Spring leaf-out near 81152 came on Mar 23 in 2026, 25 days earlier than the 1991–2020 average (Apr 17), according to the USA National Phenology Network Spring Index.

What kind of onions grow in San Luis, CO?

Intermediate onions: the longest day near 81152 is 14 h 43 min, so day-neutral types bulb best; long-day varieties may not bulb fully.