Greeley, Colorado: planting zone & frost dates
Greeley is in USDA plant hardiness zone 5b, where the average coldest winter night reaches -15 to -10°F (-26.1 to -23.3°C). The typical last spring frost is around May 7 and the first fall frost around Oct 3.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 14 | Sep 26 |
| Typical planning date (30% risk) | May 7 | Oct 3 |
| Median (50%) | May 2 | Oct 8 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station GREELEY UNC, CO (USC00053553), 4.0 mi (6.5 km) from the city center and 161 ft lower than the city center (-49 m). Record used for the 1991–2020 normals: 25 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Greeley
Greeley spans more than one half-zone. Share of the city's land area by zone (via its 4 ZIP codes): 5b (66%), 5a (34%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Greeley
Dates are counted from the 30%-risk frost dates above (last frost May 7, first frost Oct 3). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 12 – Mar 26 | May 14 – May 28 | — | — |
| Pepper | Feb 26 – Mar 12 | May 21 – Jun 4 | — | — |
| Lettuce | Mar 26 – Apr 9 | Apr 23 – May 14 | Apr 9 – May 21 | Jul 25 – Aug 22 |
| Green Beans | — | — | May 14 – Jun 18 | Jul 11 – Jul 25 |
| Sweet Corn | — | — | May 14 – Jun 11 | — |
| Zucchini & Summer Squash | Apr 9 – Apr 16 | May 14 – May 28 | May 14 – Jun 4 | Jul 11 – Jul 25 |
| Cucumber | Apr 9 – Apr 16 | May 21 – May 28 | May 14 – Jun 4 | Jul 11 – Jul 25 |
| Carrot | — | — | Apr 16 – May 21 | Jul 11 – Jul 25 |
| Onion | Feb 12 – Feb 26 | Apr 9 – Apr 23 | — | — |
| Potato | — | Apr 9 – Apr 30 | — | — |
| Basil | Mar 26 – Apr 9 | May 21 – Jun 4 | May 21 – Jun 11 | — |
| Spinach | — | — | Mar 26 – Apr 23 | Aug 8 – Sep 5 |
| Kale | Mar 12 – Mar 26 | Apr 9 – Apr 30 | Apr 9 – Apr 30 | Jul 25 – Aug 22 |
| Broccoli | Mar 12 – Mar 26 | Apr 23 – May 14 | — | Jul 11 – Jul 25 |
| Peas | — | — | Mar 26 – Apr 16 | Jul 25 – Aug 8 |
| Eggplant | Feb 26 – Mar 12 | May 21 – Jun 4 | — | — |
| Cabbage | Mar 12 – Mar 26 | Apr 9 – Apr 23 | — | Jul 11 – Jul 25 |
| Radish | — | — | Apr 2 – May 21 | Aug 22 – Sep 19 |
| Strawberry | — | Apr 9 – Apr 30 | — | — |
| Beets | — | — | Apr 16 – May 28 | Jul 25 – Aug 8 |
Nearby cities in Colorado
- Loveland — zone 5b, last frost May 15, first frost Sep 25
- Fort Collins — zone 5b, last frost May 7, first frost Oct 2
- Longmont — zone 5b, last frost May 13, first frost Oct 1
- Thornton — zone 6a, last frost May 7, first frost Oct 4
- Broomfield — zone 6a, last frost May 7, first frost Oct 4
- Westminster — zone 6a, last frost May 7, first frost Oct 4
More: all Colorado cities · other zone 5b cities: Madison, WI, Des Moines, IA, Aurora, IL, Fort Collins, CO, Naperville, IL, Rockford, IL, Elgin, IL, Green Bay, WI
Greeley gardening questions
When is the last frost in Greeley, CO?
Plan around May 7. At NOAA's Greeley Unc, CO station, 4.0 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by May 2, and after May 14 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 20. The last frost is fairly predictable here: only 27 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Greeley, CO?
Start seeds indoors Mar 12 – Mar 26 and set transplants outside May 14 – May 28, once nights stay above 50°F and the soil is near 60°F. That leaves 149 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Greeley?
About 159 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 139 days, and in 1 year in 10 it runs 178 days or more. In fall there is a 10% chance of frost by Sep 26 and a 30% chance by Oct 3. That ranks 5th longest of 16 Colorado cities on this site.
When should I plant a fall garden in Greeley?
Count back from the first fall frost (Oct 3): transplant broccoli Jul 11 – Jul 25; sow kale Jul 25 – Aug 22; sow lettuce Jul 25 – Aug 22; sow radishes Aug 22 – Sep 19. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 18. How the math works: succession and fall planting.
Did Greeley's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Greeley is zone 5b on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
Is all of Greeley in zone 5b?
No. Zone 5b covers about 66% of the city's land; the rest is in 5a (34%), measured across the city's 4 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.