Frost Dates for Calhan, CO 80808
Last spring frost May 21 · First fall frost September 22 · 124 frost-free days · USDA Zone 5b
ZIP 80808 has about 6,520 people.
Moderate season: 124 frost-free days. Spring frost risk spans April 29–June 13 (45 days). Fall frost risk spans September 5–October 9 (34 days).
Frost probability for 80808
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | June 13 | May 21 | April 29 |
| Fall (first frost) | September 5 | September 22 | October 9 |
Dates come from NOAA 1971–2000 freeze probabilities at RUSH 1N (24.0 km away); the 50% date is the median year.
Which crops fit a 124-day season in Calhan
In Calhan (124 frost-free days, a moderate season), 35 of 56 planner crops fit outright, 15 get two plantings, 5 need an indoor start, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Apr 16 | Jun 4–Jun 11 | 82 | fits: 80 days to maturity, 82 available after Jun 4. | — |
| Pepper | Apr 9 | Jun 4–Jun 11 | 82 | fits: 75 days to maturity, 82 available after Jun 4. | — |
| Lettuce | Mar 26 | Apr 23–Apr 30 | 159 | two-plantings: Plant Apr 23 and again by Aug 1; both mature before Sep 29. | Aug 1 |
| Carrots | — | Apr 30–May 7 | 166 | fits: 70 days to maturity, 166 available after Apr 30. | Jul 21 |
| Cucumber | Apr 30 | Jun 4–Jun 11 | 96 | fits: 60 days to maturity, 96 available after Jun 4. | Jun 26 |
| Beans | — | May 28–Jun 11 | 110 | fits: 60 days to maturity, 110 available after May 28. | Jul 3 |
| Peas | — | Mar 26–Jun 4 | 187 | fits: 65 days to maturity, 187 available after Mar 26. | Jul 12 |
| Zucchini | May 7 | Jun 4–Jun 11 | 96 | fits: 55 days to maturity, 96 available after Jun 4. | Jul 1 |
| Onion | Feb 26 | Apr 23–May 7 | 159 | fits: 100 days to maturity, 159 available after Apr 23. | — |
| Spinach | — | Mar 26–May 14 | 201 | two-plantings: Plant Mar 26 and again by Aug 20; both mature before Oct 13. | Aug 20 |
| Kale | Mar 12 | Apr 23–May 7 | 173 | two-plantings: Plant Apr 23 and again by Aug 5; both mature before Oct 13. | Aug 5 |
| Broccoli | Mar 26 | Apr 23–May 7 | 159 | fits: 80 days to maturity, 159 available after Apr 23. | Jun 27 |
| Cabbage | Mar 26 | Apr 23–May 7 | 173 | fits: 70 days to maturity, 173 available after Apr 23. | Jul 21 |
| Radish | — | Mar 26–Jun 18 | 187 | two-plantings: Plant Mar 26 and again by Aug 21; both mature before Sep 29. | Aug 21 |
| Beets | — | Mar 26–Jun 18 | 187 | two-plantings: Plant Mar 26 and again by Jul 22; both mature before Sep 29. | Jul 22 |
| Potatoes | — | May 7–May 14 | 145 | fits: 90 days to maturity, 145 available after May 7. | — |
| Garlic | — | Sep 22 | 229 | overwinter: Plant Sep 22 to Oct 13; harvest the following summer. | Oct 13 |
| Strawberry | — | Apr 16–Jun 11 | 180 | perennial: A perennial: plant Apr 16; it fruits from the following year and keeps producing for several years. | — |
| Corn | Apr 23 | May 28–Jun 4 | 96 | fits: 75 days to maturity, 96 available after May 28. | Jun 4 |
| Pumpkin | May 7 | Jun 4–Jun 4 | 89 | head-start: Even planted out Jun 4, the outdoor season is about 11 days short; choose an early variety or grow under cover. | — |
| Cauliflower | Apr 9 | May 14–May 28 | 138 | fits: 75 days to maturity, 138 available after May 14. | Jul 2 |
| Swiss Chard | Mar 26 | May 7–May 7 | 145 | two-plantings: Plant May 7 and again by Jul 22; both mature before Sep 29. | Jul 22 |
| Arugula | — | Mar 26–Jun 18 | 201 | two-plantings: Plant Mar 26 and again by Aug 20; both mature before Oct 13. | Aug 20 |
| Brussel Sprouts | Mar 26 | Apr 23–May 7 | 173 | fits: 100 days to maturity, 173 available after Apr 23. | Jun 21 |
| Butternut Squash | May 7 | Jun 4–Jun 11 | 89 | head-start: Even planted out Jun 4, the outdoor season is about 11 days short; choose an early variety or grow under cover. | — |
| Eggplant | Apr 2 | Jun 4–Jun 11 | 82 | fits: 70 days to maturity, 82 available after Jun 4. | — |
| Okra | Apr 23 | May 28–Jun 4 | 103 | fits: 55 days to maturity, 103 available after May 28. | Jul 1 |
| Basil | Apr 16 | Jun 11–Jun 11 | 89 | fits: 60 days to maturity, 89 available after Jun 11. | Jun 26 |
| Cilantro | — | Apr 23–May 14 | 159 | two-plantings: Plant Apr 23 and again by Jul 27; both mature before Sep 29. | Jul 27 |
| Parsley | Mar 12 | May 28–Jun 4 | 124 | fits: 70 days to maturity, 124 available after May 28. | Jul 7 |
| Celery | Mar 12 | May 28–Jun 11 | 124 | fits: 120 days to maturity, 124 available after May 28. | — |
| Scallions | Mar 12 | Apr 23–May 7 | 173 | two-plantings: Plant Apr 23 and again by Jul 31; both mature before Oct 13. | Jul 31 |
| Turnip | — | Apr 23–May 7 | 173 | two-plantings: Plant Apr 23 and again by Aug 10; both mature before Oct 13. | Aug 10 |
| Kohlrabi | — | Apr 9–Apr 23 | 187 | two-plantings: Plant Apr 9 and again by Aug 5; both mature before Oct 13. | Aug 5 |
| Bok Choy | Apr 23 | May 14–May 21 | 138 | two-plantings: Plant May 14 and again by Aug 1; both mature before Sep 29. | Aug 1 |
| Collards | Mar 12 | Apr 23–May 7 | 173 | two-plantings: Plant Apr 23 and again by Jul 31; both mature before Oct 13. | Jul 31 |
| Cantaloupe | May 7 | Jun 4–Jun 11 | 82 | head-start: Even planted out Jun 4, the outdoor season is about 3 days short; choose an early variety or grow under cover. | — |
| Chives | Feb 26 | May 28–Jun 4 | 138 | fits: 90 days to maturity, 138 available after May 28. | — |
| Dill | — | Mar 26–Jun 18 | 187 | two-plantings: Plant Mar 26 and again by Jul 22; both mature before Sep 29. | Jul 22 |
| Oregano | Mar 12 | May 28–Jun 4 | 138 | fits: 80 days to maturity, 138 available after May 28. | — |
| Rosemary | Feb 26 | May 28–Jun 4 | 124 | fits: 80 days to maturity, 124 available after May 28. | — |
| Sage | Mar 26 | May 28–Jun 4 | 138 | fits: 75 days to maturity, 138 available after May 28. | — |
| Thyme | Mar 12 | May 28–Jun 4 | 138 | fits: 90 days to maturity, 138 available after May 28. | — |
| Calendula | Apr 9 | May 7–May 21 | 145 | two-plantings: Plant May 7 and again by Jul 27; both mature before Sep 29. | Jul 27 |
| Cosmos | Apr 23 | May 21–Jun 4 | 110 | fits: 60 days to maturity, 110 available after May 21. | Jun 26 |
| Lavender | Feb 26 | May 21–Jun 4 | 145 | fits: 90 days to maturity, 145 available after May 21. | — |
| Marigolds | Apr 9 | May 21–May 28 | 110 | fits: 50 days to maturity, 110 available after May 21. | Jul 6 |
| Melons | May 7 | Jun 4–Jun 11 | 82 | head-start: Even planted out Jun 4, the outdoor season is about 3 days short; choose an early variety or grow under cover. | — |
| Mint | — | May 21–Jun 4 | 145 | fits: 90 days to maturity, 145 available after May 21. | — |
| Nasturtiums | Apr 23 | May 21–May 28 | 110 | fits: 55 days to maturity, 110 available after May 21. | Jul 1 |
| Pole Beans | — | May 28–Jun 11 | 103 | fits: 65 days to maturity, 103 available after May 28. | Jun 21 |
| Spaghetti Squash | May 7 | Jun 4–Jun 11 | 89 | head-start: Even planted out Jun 4, the outdoor season is about 1 days short; choose an early variety or grow under cover. | — |
| Sunflowers | — | May 21–Jun 4 | 110 | fits: 70 days to maturity, 110 available after May 21. | Jun 16 |
| Tomatillos | Mar 26 | May 28–Jun 4 | 89 | fits: 75 days to maturity, 89 available after May 28. | — |
| Watermelon | May 7 | May 28–Jun 4 | 89 | fits: 80 days to maturity, 89 available after May 28. | — |
| Yellow Squash | May 7 | Jun 4–Jun 11 | 96 | fits: 55 days to maturity, 96 available after Jun 4. | Jul 1 |
| Zinnias | Apr 23 | May 21–Jun 4 | 110 | fits: 60 days to maturity, 110 available after May 21. | Jun 26 |
Month by month in Calhan
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start indoors: Chives (Feb 26), Lavender (Feb 26), Onion (Feb 26), Rosemary (Feb 26). |
| March | Start indoors: Celery (Mar 12), Collards (Mar 12), Kale (Mar 12), Oregano (Mar 12), Parsley (Mar 12), Scallions (Mar 12), +8 more. Direct sow from: Arugula (Mar 26), Beets (Mar 26), Dill (Mar 26), Peas (Mar 26), Radish (Mar 26), Spinach (Mar 26). |
| April | Start indoors: Eggplant (Apr 2), Calendula (Apr 9), Cauliflower (Apr 9), Marigolds (Apr 9), Pepper (Apr 9), Basil (Apr 16), +8 more. Direct sow from: Kohlrabi (Apr 9), Cilantro (Apr 23), Turnip (Apr 23), Carrots (Apr 30). Transplant from: Broccoli (Apr 23), Brussel Sprouts (Apr 23), Cabbage (Apr 23), Collards (Apr 23), Kale (Apr 23), Lettuce (Apr 23), +2 more. Plant: Strawberry (Apr 16). |
| May | Start indoors: Butternut Squash (May 7), Cantaloupe (May 7), Melons (May 7), Pumpkin (May 7), Spaghetti Squash (May 7), Watermelon (May 7), +2 more. Direct sow from: Potatoes (May 7), Sunflowers (May 21), Beans (May 28), Pole Beans (May 28). Transplant from: Calendula (May 7), Swiss Chard (May 7), Bok Choy (May 14), Cauliflower (May 14), Cosmos (May 21), Lavender (May 21), +15 more. Last frost around May 21. |
| June | Transplant from: Butternut Squash (Jun 4), Cantaloupe (Jun 4), Cucumber (Jun 4), Eggplant (Jun 4), Melons (Jun 4), Pepper (Jun 4), +6 more. Last sowing dates: Corn (Jun 4), Sunflowers (Jun 16), Brussel Sprouts (Jun 21), Pole Beans (Jun 21), Basil (Jun 26), Cosmos (Jun 26), +3 more. |
| July | Last sowing dates: Nasturtiums (Jul 1), Okra (Jul 1), Yellow Squash (Jul 1), Zucchini (Jul 1), Cauliflower (Jul 2), Beans (Jul 3), +12 more. |
| August | Last sowing dates: Bok Choy (Aug 1), Lettuce (Aug 1), Kale (Aug 5), Kohlrabi (Aug 5), Turnip (Aug 10), Arugula (Aug 20), +2 more. |
| September | Direct sow from: Garlic (Sep 22). First frost around September 22. |
| October | Last sowing dates: Garlic (Oct 13). |
| November | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
| December | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
Frequently Asked Questions
What is the last frost date for Calhan, CO (ZIP 80808)?
The median last spring frost date for Calhan, CO (ZIP code 80808) is around May 21. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area. One year in ten frost ends before April 29; one in ten it runs past June 13.
What is the first fall frost date in Calhan, CO?
The median first fall frost date for Calhan, CO is around September 22. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses. The first frost arrives around September 5 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Calhan, CO?
The frost-free growing season in Calhan is about 124 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side. In Calhan (124 frost-free days, a moderate season), 35 of 56 planner crops fit outright, 15 get two plantings, 5 need an indoor start, 1 crop is perennial.
What USDA hardiness zone is Calhan, CO?
Calhan, CO is in USDA hardiness zone 5b (2023 USDA Plant Hardiness Zone Map). Zones come from the average coldest winter temperature, so they tell you which perennials survive the winter; the frost dates on this page tell you when to plant.
When should I start tomatoes indoors in Calhan, CO?
Start tomatoes indoors Apr 16 and plant out Jun 4 in Calhan. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Calhan?
Two: plant Apr 23 and again by Aug 1; both mature before Sep 29.
When do I plant garlic in Calhan?
Sep 22 to Oct 13; it overwinters and is ready the following summer.
Can I grow Butternut Squash in Calhan?
Yes, with help. Even planted out Jun 4, the outdoor season is about 11 days short; choose an early variety or grow under cover.
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