USDA zone 5b in Colorado
USDA plant hardiness zone 5b covers 96 locations across Colorado (average annual extreme minimum −15 to −10 °F): Air Force Academy, CO, Akron, CO, Allenspark, CO, Aspen Park, CO, Atwood, CO, Black Forest, CO, and 90 more. Average last spring frost across this group ranges April 30 (Denver) to June 21 (Gunnison), and growing seasons run 71–165 days (Eldora to Haswell) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Colorado location's own frost dates; the printable planting calendar uses Ponderosa Park, this group's median-season location.
- USDA zone
- 5b−15 to −10 °F
- Last frost range
- Apr 30–Jun 21avg, 32°F
- First frost range
- Sep 2–Oct 14avg, 32°F
- Growing season range
- 71–165days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Air Force Academy | — | Monument 3s | May 17 | Oct 1 | 136 |
| Akron | Otis | Akron 4 E | May 8 | Oct 6 | 149 |
| Allenspark | — | Estes Park 3 Sse | May 30 | Sep 17 | 109 |
| Aspen Park | Brook Forest | Bailey | Jun 16 | Sep 8 | 84 |
| Atwood | — | Leroy 5 Wsw | May 10 | Oct 6 | 147 |
| Black Forest | Gleneagle | Black Forest 6wnw | May 11 | Oct 6 | 147 |
| Brighton | Fort Lupton, Hudson, Derby | Brighton 3 Se | May 3 | Oct 7 | 155 |
| Brook Forest | Montezuma | Grant | Jun 15 | Sep 9 | 84 |
| Brush | Hillrose | Akron Washington Co Ap | May 6 | Oct 8 | 155 |
| Capulin | — | Manassa | May 28 | Sep 21 | 115 |
| Castle Rock | Castle Pines, Franktown | Castle Rock | May 9 | Oct 2 | 143 |
| Cathedral | — | Blue Mesa Lake | Jun 9 | Sep 16 | 96 |
| Cedaredge | — | Cedaredge 3e | May 3 | Oct 9 | 156 |
| Coal Creek | — | Ralston Rsvr | May 3 | Oct 14 | 161 |
| Coal Creek | Central, Rollinsville | Coal Creek Canyon | Jun 5 | Sep 16 | 103 |
| Coaldale | Howard, Poncha Springs, Bonanza, Garfield | Salida | May 29 | Sep 20 | 112 |
| Collbran | — | Collbran 1wsw | May 17 | Sep 30 | 136 |
| Colona | — | Cimarron | Jun 20 | Sep 10 | 81 |
| Colorado Springs | Cascade-Chipita Park, Manitou Springs, Goldfield | Ruxton Park | Jun 3 | Sep 17 | 102 |
| Colorado Springs | — | Cumbre Vista - Colorado Spgs 1 | May 9 | Oct 6 | 150 |
| Colorado Springs | Peyton, Calhan | Colorado Springs Muni Ap | May 3 | Oct 8 | 158 |
| Cope | Deer Trail | Lindon 5 Wnw | May 15 | Oct 2 | 139 |
| Cope | Arriba, Genoa | Shaw 4ene | May 12 | Oct 4 | 143 |
| Cope | Joes, Kirk | Joes | May 3 | Oct 9 | 158 |
| Craig | — | Craig Moffat Co Ap | Jun 6 | Sep 12 | 96 |
| Del Norte | — | Monte Vista 2w | Jun 11 | Sep 13 | 92 |
| Denver | — | Denver Water Dept | Apr 30 | Oct 12 | 165 |
| Dotsero | — | Glenwood Spgs #2 | May 13 | Oct 3 | 142 |
| Downieville-Lawson-Dumont | — | Georgetown | May 30 | Sep 19 | 112 |
| Edwards | Eagle, Vail | Vail | Jun 21 | Sep 7 | 77 |
| Elbert | — | Eastonville 2 Nnw | May 29 | Sep 21 | 114 |
| Eldora | Nederland, Glendale, Ward | Boulder 14 W | Jun 21 | Sep 2 | 71 |
| Ellicott | — | Rush 1n | May 9 | Oct 4 | 146 |
| Fairplay | — | Fairplay S Park Rd | Jun 16 | Sep 9 | 83 |
| Flagler | — | Flagler 1s | May 5 | Oct 8 | 155 |
| Fleming | — | Fleming 3sw | May 4 | Oct 11 | 157 |
| Fort Collins | Laporte | Ft Collins | May 2 | Oct 7 | 157 |
| Fort Collins | Windsor, Severance, Timnath, Wellington, Pierce | Ft Collins 4 E | May 3 | Oct 6 | 154 |
| Fort Garland | — | Blanca 4 Nw | May 25 | Sep 22 | 117 |
| Garfield | — | Buena Vista 2s | May 27 | Sep 23 | 116 |
| Golden | — | Lakewood | May 3 | Oct 7 | 155 |
| Greeley | Milliken, Eaton, Platteville, Garden | Greeley Unc | May 2 | Oct 8 | 159 |
| Guffey | Florissant | Lake George 8 Sw | Jun 2 | Sep 19 | 108 |
| Gunnison | Pitkin | Cochetopa Creek | Jun 21 | Sep 5 | 74 |
| Haswell | — | Eads | Apr 30 | Oct 13 | 165 |
| Haswell | Ordway | Ordway 21 N | May 3 | Oct 7 | 155 |
| Holyoke | Haxtun, Amherst, Paoli | Holyoke | May 11 | Oct 3 | 144 |
| Hot Sulphur Springs | — | Williams Fork Dam | Jun 12 | Sep 10 | 89 |
| Hugo | — | Hugo 1 Nw | May 10 | Oct 2 | 143 |
| Iliff | Crook | Crook | May 11 | Oct 4 | 145 |
| Indian Hills | Upper Bear Creek, Aspen Park, Kittredge, Morrison, Idledale | Evergreen | May 23 | Sep 22 | 118 |
| Johnstown | — | Loveland 2n | May 10 | Oct 1 | 142 |
| Julesburg | Venango, Chappell | Julesburg | May 7 | Oct 6 | 152 |
| Keenesburg | Lochbuie | Denver Intl Ap | May 5 | Oct 9 | 156 |
| Ken Caryl | Sterling Ranch | Kassler | May 8 | Oct 3 | 147 |
| Kit Carson | — | Kit Carson | May 10 | Oct 1 | 142 |
| Laporte | — | Buckhorn Mtn 1 E | May 21 | Sep 29 | 128 |
| Limon | Matheson, Deer Trail | Limon Wsmo | May 21 | Sep 26 | 127 |
| Longmont | Erie, Frederick, Mead, Berthoud, Dacono, Niwot | Longmont 2 Ese | May 7 | Oct 5 | 151 |
| Loveland | Estes Park | Waterdale | May 12 | Oct 1 | 141 |
| Matheson | Haswell | Karval | May 9 | Oct 6 | 149 |
| Maybell | — | Massadona 3e | May 10 | Oct 4 | 147 |
| McCoy | — | Green Mt Dam | Jun 6 | Sep 14 | 98 |
| McCoy | — | Yampa | Jun 14 | Sep 11 | 89 |
| Meeker | — | Meeker Ap | May 30 | Sep 22 | 117 |
| Moffat | — | Crestone 2 Se | May 26 | Sep 26 | 120 |
| Monument | Palmer Lake, Larkspur | Monument | May 14 | Oct 1 | 138 |
| Nunn | — | Nunn 7 Nne | May 13 | Sep 27 | 136 |
| Ouray | Ophir | Ouray | May 17 | Oct 1 | 137 |
| Pagosa Springs | Lumberton | Dulce | Jun 9 | Sep 22 | 103 |
| Parker | — | Parker | May 9 | Oct 3 | 145 |
| Placerville | Rico, Ophir | Placerville | May 26 | Sep 29 | 125 |
| Ponderosa Park * | Kiowa | Elizabeth 2nw | May 16 | Oct 2 | 137 |
| Raymer (New Raymer) | — | New Raymer 21 N | May 18 | Sep 29 | 133 |
| Red Feather Lakes | — | Rustic 9wsw | Jun 5 | Sep 16 | 101 |
| Red Feather Lakes | Warren AFB, Wellington | Virginia Dale 7 Ene | May 31 | Sep 19 | 110 |
| Roxborough Park | Louviers | Roxborough Sp | May 16 | Oct 1 | 136 |
| Saguache | — | Saguache | May 16 | Sep 28 | 135 |
| San Luis | — | San Luis 1 S | May 31 | Sep 23 | 115 |
| Sedgwick | Ovid | Sedgwick 5 S | May 6 | Oct 7 | 152 |
| Seibert | — | Seibert | May 4 | Oct 11 | 158 |
| Silver Cliff | Cotopaxi | Westcliffe | Jun 11 | Sep 9 | 89 |
| Snowmass | Woody Creek | Aspen Pitkin Co Ap | May 31 | Sep 23 | 114 |
| South Fork | — | Del Norte 3ene | May 23 | Sep 25 | 123 |
| Steamboat Springs | — | Steamboat Springs | Jun 9 | Sep 12 | 93 |
| Sterling | Padroni, Merino | Sterling | Apr 30 | Oct 9 | 161 |
| Strasburg | Byers, Deer Trail | Byers 5 Ene | May 13 | Oct 2 | 142 |
| Sugar | Crowley | Ordway 1 Ene | May 2 | Oct 8 | 159 |
| Tabernash | Fraser | Grand Lake 6 Ssw | Jun 13 | Sep 7 | 84 |
| Twin Lakes | — | Twin Lakes Rsvr | Jun 16 | Sep 10 | 85 |
| Vernon | — | Idalia | May 4 | Oct 9 | 155 |
| Westcreek | — | Cheesman | May 17 | Oct 1 | 135 |
| Wiggins | Trail Side, Snyder | Ft Morgan | May 6 | Oct 6 | 153 |
| Woodland Park | Divide | Divide 4nw | Jun 1 | Sep 21 | 110 |
| Wray | — | Wray | May 7 | Oct 6 | 151 |
| Yuma | Eckley | Yuma | May 1 | Oct 12 | 164 |
* Ponderosa Park is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Ponderosa Park, representative)
Computed from Ponderosa Park's average frost dates — the median-season location in this Coloradozone 5b group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Mar 21 – Apr 4 | May 23 – May 30 | Jul 22 – Aug 11 | — | matures comfortably |
| Pepper | Very tender | Mar 7 – Mar 21 | May 30 – Jun 6 | Jul 29 – Aug 28 | — | matures comfortably |
| Cucumber | Tender | Apr 18 – Apr 25 | May 23 – May 30 | Jul 12 – Aug 1 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 23 – May 30 | Jul 7 – Jul 22 | — | matures comfortably |
| Bush bean | Tender | — | May 23 – May 30 | Jul 12 – Jul 22 | Aug 3 – Aug 13 | matures comfortably |
| Sweet corn | Tender | — | May 16 – May 30 | Jul 15 – Aug 14 | — | matures comfortably |
| Basil | Very tender | Apr 4 – Apr 18 | May 23 – May 30 | Jun 22 – Jul 7 | — | matures comfortably |
| Lettuce | Half-hardy | Apr 4 – Apr 18 | Apr 18 – May 2 | Jun 2 – Jun 17 | Jul 20 – Aug 4 | matures comfortably |
| Pea | Hardy | — | Apr 4 – Apr 18 | May 29 – Jun 13 | Jul 10 – Jul 25 | matures comfortably |
| Spinach | Hardy | — | Apr 4 – Apr 18 | May 14 – May 24 | Jul 30 – Aug 9 | matures comfortably |
| Carrot | Half-hardy | — | Apr 25 – May 2 | Jun 24 – Jul 14 | Jun 30 – Jul 20 | matures comfortably |
| Broccoli | Half-hardy | Mar 21 – Apr 4 | Apr 18 – May 2 | Jun 12 – Jul 2 | Jul 5 – Jul 25 | matures comfortably |
Which crops fit this growing season
Using Ponderosa Park's own 137-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Ponderosa Park)
From NOAA's 1991–2020 Climate Normals at station USC00052631. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | May 28 | Jun 11 | Sep 24 | Oct 5 | 119 |
| 32°F (freeze) | May 16 | Jun 1 | Oct 2 | Oct 16 | 137 |
| 28°F | May 6 | May 19 | Oct 10 | Oct 23 | 155 |
| 24°F | Apr 29 | May 11 | Oct 20 | Nov 3 | 173 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 96 locations is 2,322; Ponderosa Park's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 2,321 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 4,371 | cool-season crops (brassicas, greens) |
Hardiness zone 5b in Colorado
Zone 5b means an average annual extreme minimum winter temperature of about −15 to −10 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. Colorado spans 7 hardiness zones in this dataset — see all Colorado locations for the full range, including zones4a, 4b, 5a, 6a, 6b, 7a.
Explore zone 5b in other states at zone 5b, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 5b mean in Colorado?
- Zone 5b means an average annual extreme minimum winter temperature of −15 to −10 °F — the standard USDA measure of which perennials survive winter. 96 locations in Colorado fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in Colorado's zone 5b is the growing season longest?
- Haswell runs the longest season on this page at about 165 days; Eldora is shortest at about 71 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in Colorado's zone 5b?
- Using Ponderosa Park's frost dates (this page's median-season location): start seeds indoors about Mar 21 – Apr 4, then transplant outside about May 23 – May 30. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in Colorado's zone 5b have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 96 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.