Black Hawk, CO frost dates
Last spring frostJun 5median date
First fall frostSep 16median date
Growing season103 daysfrost-free
Hardiness zone5bZone 5b
How Black Hawk compares
- In 8 years out of 10, the last spring frost in Black Hawk falls between May 23 and June 19, a 27-day window. The first fall frost falls between September 2 and September 28.
- The median last frost is 25 days later than the Colorado median of May 11.
- Its 103-day growing season is longer than 14% of the 374 Colorado places with a regular frost season (state median 146 days).
- The last frost is 35 days later than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 211 nights a year at or below 32°F.
- Compared with Boulder, CO, 29 km away, the last frost here is 30 days later than there and the growing season is 49 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | May 23 |
| 50% (median) | June 5 |
| 10% (safe for tender plants) | June 19 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 2 |
| 50% (median) | September 16 |
| 90% (late) | September 28 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Black Hawk, CO
Black Hawk, CO frost dates — last frost Jun 5, first frost Sep 16, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Mar 13 to Mar 27Transplant outside: May 8 to May 22
Start indoors: Mar 27 to Apr 10Transplant outside: Jun 19 to Jul 3
Start indoors: Mar 27 to Apr 10Transplant outside: Jun 19 to Jul 3
Start indoors: Apr 10 to Apr 24Transplant outside: Jun 12 to Jun 26
Start indoors: Apr 10 to Apr 24Transplant outside: May 15 to May 29Sow outdoors: May 8 to Jun 12Plant for fall: Jul 22 to Aug 19
Start indoors: Apr 10 to Apr 24Transplant outside: May 8 to May 22Sow outdoors: May 8 to May 22Plant for fall: Jul 8 to Jul 29
Start indoors: Apr 10 to Apr 24Transplant outside: May 22 to Jun 5
Start indoors: Apr 10 to Apr 24Transplant outside: May 15 to May 29
Start indoors: Apr 10 to Apr 24Transplant outside: May 22 to Jun 5
Start indoors: Apr 24 to May 8Transplant outside: Jun 26 to Jul 10Sow outdoors: Jun 26 to Jul 10
Start indoors: Apr 24 to May 8Transplant outside: Jun 12 to Jun 26
Sow outdoors: Apr 24 to May 15Plant for fall: Jun 24 to Jul 15
Sow outdoors: Apr 24 to May 15Plant for fall: Jul 22 to Aug 12
Sow outdoors: May 1 to Jun 12Plant for fall: Aug 5 to Aug 26
Start indoors: May 8 to May 15Transplant outside: Jun 19 to Jun 26Sow outdoors: Jun 12 to Jun 26
Start indoors: May 8 to May 15Sow outdoors: Jun 12 to Jun 26
Start indoors: May 8 to May 15Sow outdoors: Jun 12 to Jun 26
Start indoors: May 8 to May 15Transplant outside: Jun 19 to Jul 3
Sow outdoors: May 15 to Jun 12
Sow outdoors: May 15 to Jun 12Plant for fall: Jul 8 to Jul 22
Sow outdoors: May 15 to Jun 5
Sow outdoors: May 22 to Jun 19Plant for fall: Jul 8 to Jul 22
Sow outdoors: May 22 to Jun 12Plant for fall: Jul 22 to Aug 12
Sow outdoors: Jun 12 to Jul 3
Sow outdoors: Jun 12 to Jun 26
Transplant outside: Jun 19 to Jul 10
Plant for fall: Sep 2 to Oct 7
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Black Hawk, CO
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Mar 13 – Mar 27 | May 8 – May 22 | — | — |
| Peppers | Mar 27 – Apr 10 | Jun 19 – Jul 3 | — | — |
| Eggplant | Mar 27 – Apr 10 | Jun 19 – Jul 3 | — | — |
| Tomatoes | Apr 10 – Apr 24 | Jun 12 – Jun 26 | — | — |
| Lettuce | Apr 10 – Apr 24 | May 15 – May 29 | May 8 – Jun 12 | Jul 22 – Aug 19 |
| Kale | Apr 10 – Apr 24 | May 8 – May 22 | May 8 – May 22 | Jul 8 – Jul 29 |
| Broccoli | Apr 10 – Apr 24 | May 22 – Jun 5 | — | — |
| Cabbage | Apr 10 – Apr 24 | May 15 – May 29 | — | — |
| Cauliflower | Apr 10 – Apr 24 | May 22 – Jun 5 | — | — |
| Okra | Apr 24 – May 8 | Jun 26 – Jul 10 | Jun 26 – Jul 10 | — |
| Basil | Apr 24 – May 8 | Jun 12 – Jun 26 | — | — |
| Peas | — | — | Apr 24 – May 15 | Jun 24 – Jul 15 |
| Spinach | — | — | Apr 24 – May 15 | Jul 22 – Aug 12 |
| Radishes | — | — | May 1 – Jun 12 | Aug 5 – Aug 26 |
| Cucumbers | May 8 – May 15 | Jun 19 – Jun 26 | Jun 12 – Jun 26 | — |
| Zucchini & Summer Squash | May 8 – May 15 | — | Jun 12 – Jun 26 | — |
| Winter Squash & Pumpkins Warning: Your frost-free season is about 103 days, which is tight for winter squash & pumpkins (100+ days). Choose early varieties and use transplants or row covers. | May 8 – May 15 | — | Jun 12 – Jun 26 | — |
| Melons & Watermelon | May 8 – May 15 | Jun 19 – Jul 3 | — | — |
| Carrots | — | — | May 15 – Jun 12 | — |
| Beets | — | — | May 15 – Jun 12 | Jul 8 – Jul 22 |
| Potatoes | — | — | May 15 – Jun 5 | — |
| Swiss Chard | — | — | May 22 – Jun 19 | Jul 8 – Jul 22 |
| Cilantro | — | — | May 22 – Jun 12 | Jul 22 – Aug 12 |
| Green Beans | — | — | Jun 12 – Jul 3 | — |
| Sweet Corn | — | — | Jun 12 – Jun 26 | — |
| Sweet Potatoes Warning: Your frost-free season is about 103 days, which is tight for sweet potatoes (100+ days). Choose early varieties and use transplants or row covers. | — | Jun 19 – Jul 10 | — | — |
| Garlic | — | — | — | Sep 2 – Oct 7 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Coal Creek Canyon, CO weather station, 12 km away (elevation 8,950 ft (2,728 m)).
Frost dates near Black Hawk
- Central City Jun 5 · Sep 16
- Rollinsville Jun 5 · Sep 16
- Dumont May 30 · Sep 19
- Idaho Springs May 30 · Sep 19
- Pinecliffe Jun 5 · Sep 16
- Nederland Jun 21 · Sep 2
- Empire May 30 · Sep 19
- Eldorado Springs May 24 · Sep 23
- Georgetown May 30 · Sep 19
- Golden May 3 · Oct 7
Frequently asked questions
When is the last frost in Black Hawk, CO?
The median last spring frost in Black Hawk, CO is June 5. There is still about a 10% chance of frost after June 19, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Black Hawk, CO?
The median first fall frost is September 16, with about a 10% chance of frost before September 2.
How long is the growing season in Black Hawk, CO?
About 103 days between the median last spring frost and first fall frost.
What planting zone is Black Hawk, CO?
Black Hawk, CO is in USDA hardiness zone 5b.