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

Planting zone for 81652 — Silt, CO

ZIP code 81652 (Silt, Garfield County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 11 and the first fall frost October 4.

Where ZIP 81652 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.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostMay 11
First frostOct 4
2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Silt, 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 Silt, CO

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 11median — 50% chance of a later frost
Safe for tender plantsMay 27only 10% chance of frost after
First fall frostOctober 4median — 10% chance by Sep 23
Growing season143 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 28 and returns around October 15.

From the NOAA station Rifle Garfield Co. Airport, CO — 5 miles away, elevation 5,532 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 81652

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 30 – Apr 13
SpinachSow outdoors · Mar 30 – Apr 20
Broccoli, cabbageStart indoors · Mar 2 – Mar 16
Broccoli, cabbageTransplant · Apr 20 – May 4
Onion setsPlant outdoors · Apr 13 – Apr 27
PotatoesPlant outdoors · Apr 20 – May 4
LettuceSow outdoors · Apr 13 – Apr 27
Carrots, beetsSow outdoors · Apr 20 – May 4
TomatoesStart indoors · Mar 16 – Mar 30
TomatoesTransplant · May 18 – Jun 1
Peppers, eggplantStart indoors · Mar 2 – Mar 16
Peppers, eggplantTransplant · May 25 – Jun 8
BeansSow outdoors · May 18 – Jun 1
Sweet cornSow outdoors · May 18 – Jun 1
Cucumbers, squashSow outdoors · May 18 – Jun 1
Fall lettuce, spinachSow outdoors · Aug 9 – Aug 23
GarlicPlant cloves · Sep 20 – Oct 25
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 11) and first fall frost (Oct 4) 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 81652 came on Mar 18 — 18 days earlier than the 1991–2020 average (Apr 5).

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 6a in Colorado

563 plants native to the lower 48 states, recorded in Colorado, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 28

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 104

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 251

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 167

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 4

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °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 Silt, CO.

Soil in Silt, CO

The soil mapped at the center of ZIP 81652 is Potts — loam, well drained.

TextureLoama good balance for most vegetables
pH7.6slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Potts loam, 6 to 12 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 81652; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Silt, CO

Summer high92 °Faverage high, July
Winter low13 °Faverage low, January
Hot days54days a year at 90 °F or more
Freezing nights173nights a year at 32 °F or less
Growing degree days2,679base 50 °F — the season’s usable heat
Longest day14 h 57 mindaylight on June 21
Shortest day9 h 23 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation10.7 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 37 °F, low 13 °F 37°13° JanFebruary: average high 44 °F, low 20 °F 44°20° FebMarch: average high 55 °F, low 27 °F 55°27° MarApril: average high 63 °F, low 33 °F 63°33° AprMay: average high 74 °F, low 40 °F 74°40° MayJune: average high 86 °F, low 48 °F 86°48° JunJuly: average high 92 °F, low 55 °F 92°55° JulAugust: average high 89 °F, low 54 °F 89°54° AugSeptember: average high 80 °F, low 45 °F 80°45° SepOctober: average high 66 °F, low 34 °F 66°34° OctNovember: average high 50 °F, low 23 °F 50°23° NovDecember: average high 37 °F, low 14 °F 37°14° Dec

Precipitation by month inches

0″1″2″January: 0.70 in precipitation 0.7 JanFebruary: 0.60 in precipitation 0.6 FebMarch: 0.76 in precipitation 0.8 MarApril: 1.01 in precipitation 1.0 AprMay: 1.14 in precipitation 1.1 MayJune: 0.68 in precipitation 0.7 JunJuly: 0.96 in precipitation 1.0 JulAugust: 1.07 in precipitation 1.1 AugSeptember: 1.34 in precipitation 1.3 SepOctober: 1.27 in precipitation 1.3 OctNovember: 0.63 in precipitation 0.6 NovDecember: 0.57 in precipitation 0.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Rifle Garfield Co. Airport, CO (5 mi away); precipitation: Rifle Garfield Co. Airport, CO (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

816476a
New Castle, CO · 11 mi
816366b
Battlement Mesa, CO · 19 mi
816026a
Glenwood Springs, CO · 19 mi
816016a
Glenwood Springs, CO · 20 mi
816356a
Parachute, CO · 22 mi
816246a
Collbran, CO · 22 mi
816506a
Rifle, CO · 31 mi
816465b
Molina, CO · 31 mi

Colorado planting zones →

Questions about 81652

What planting zone is ZIP code 81652?

ZIP code 81652 (Silt, CO) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Silt, CO?

The median last spring frost (32 °F) near 81652 is May 11; after May 27 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Rifle Garfield Co. Airport station.

When is the first frost in Silt, CO?

The median first fall frost near 81652 is October 4, giving a median frost-free growing season of 143 days.

When should I plant tomatoes in 81652?

Start tomato seeds indoors around Mar 16 – Mar 30 and set transplants outside around May 18 – Jun 1, one to three weeks after the median last frost.

How much rain and snow does 81652 get?

About 10.7 inches of precipitation a year (NOAA 1991–2020 normals, Rifle Garfield Co. Airport station).

How hot do summers get in Silt, CO?

The average high peaks at 92 °F in July, with about 54 days a year at 90 °F or more.

What kind of soil does 81652 have?

The USDA soil survey maps Potts at the center of ZIP 81652: loam, well drained, pH about 7.6 (slightly alkaline).

Did spring come early in Silt, CO in 2026?

Spring leaf-out near 81652 came on Mar 18 in 2026, 18 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Silt, CO?

Intermediate onions: the longest day near 81652 is 14 h 57 min, so day-neutral types bulb best; long-day varieties may not bulb fully.