Frost Dates for Alamosa, CO 81101
Last spring frost June 9 · First fall frost September 14 · 97 frost-free days · USDA Zone 4b
ZIP 81101 has about 15,600 people.
Short season: 97 frost-free days. Spring frost risk spans May 24–June 23 (30 days). Fall frost risk spans September 1–September 30 (29 days).
Frost probability for 81101
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | June 23 | June 9 | May 24 |
| Fall (first frost) | September 1 | September 14 | September 30 |
Dates come from NOAA 1971–2000 freeze probabilities at ALAMOSA-BERGMAN FLD (3.7 km away); the 50% date is the median year.
Which crops fit a 97-day season in Alamosa
In Alamosa (97 frost-free days, a short season), 29 of 56 planner crops fit outright, 14 get two plantings, 5 need an indoor start, 7 don't reliably mature, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | May 5 | Jun 23–Jun 30 | 55 | no-fit: Needs 80 days; Alamosa has 55 after Jun 23. | — |
| Pepper | Apr 28 | Jun 23–Jun 30 | 55 | head-start: Even planted out Jun 23, the outdoor season is about 20 days short; choose an early variety or grow under cover. | — |
| Lettuce | Apr 14 | May 12–May 19 | 132 | two-plantings: Plant May 12 and again by Jul 24; both mature before Sep 21. | Jul 24 |
| Carrots | — | May 19–May 26 | 139 | fits: 70 days to maturity, 139 available after May 19. | Jul 13 |
| Cucumber | May 19 | Jun 23–Jun 30 | 69 | fits: 60 days to maturity, 69 available after Jun 23. | — |
| Beans | — | Jun 16–Jun 30 | 83 | fits: 60 days to maturity, 83 available after Jun 16. | Jun 25 |
| Peas | — | Apr 14–Jun 23 | 160 | fits: 65 days to maturity, 160 available after Apr 14. | Jul 4 |
| Zucchini | May 26 | Jun 23–Jun 30 | 69 | fits: 55 days to maturity, 69 available after Jun 23. | — |
| Onion | Mar 17 | May 12–May 26 | 132 | fits: 100 days to maturity, 132 available after May 12. | — |
| Spinach | — | Apr 14–Jun 2 | 174 | two-plantings: Plant Apr 14 and again by Aug 12; both mature before Oct 5. | Aug 12 |
| Kale | Mar 31 | May 12–May 26 | 146 | two-plantings: Plant May 12 and again by Jul 28; both mature before Oct 5. | Jul 28 |
| Broccoli | Apr 14 | May 12–May 26 | 132 | fits: 80 days to maturity, 132 available after May 12. | Jun 19 |
| Cabbage | Apr 14 | May 12–May 26 | 146 | fits: 70 days to maturity, 146 available after May 12. | Jul 13 |
| Radish | — | Apr 14–Jul 7 | 160 | two-plantings: Plant Apr 14 and again by Aug 13; both mature before Sep 21. | Aug 13 |
| Beets | — | Apr 14–Jul 7 | 160 | two-plantings: Plant Apr 14 and again by Jul 14; both mature before Sep 21. | Jul 14 |
| Potatoes | — | May 26–Jun 2 | 118 | fits: 90 days to maturity, 118 available after May 26. | — |
| Garlic | — | Sep 14 | 202 | overwinter: Plant Sep 14 to Oct 5; harvest the following summer. | Oct 5 |
| Strawberry | — | May 5–Jun 30 | 153 | perennial: A perennial: plant May 5; it fruits from the following year and keeps producing for several years. | — |
| Corn | May 12 | Jun 16–Jun 23 | 69 | head-start: Even planted out Jun 16, the outdoor season is about 6 days short; choose an early variety or grow under cover. | — |
| Pumpkin | May 26 | Jun 23–Jun 23 | 62 | no-fit: Needs 100 days; Alamosa has 62 after Jun 23. | — |
| Cauliflower | Apr 28 | Jun 2–Jun 16 | 111 | fits: 75 days to maturity, 111 available after Jun 2. | Jun 24 |
| Swiss Chard | Apr 14 | May 26–May 26 | 118 | fits: 55 days to maturity, 118 available after May 26. | Jul 14 |
| Arugula | — | Apr 14–Jul 7 | 174 | two-plantings: Plant Apr 14 and again by Aug 12; both mature before Oct 5. | Aug 12 |
| Brussel Sprouts | Apr 14 | May 12–May 26 | 146 | fits: 100 days to maturity, 146 available after May 12. | Jun 13 |
| Butternut Squash | May 26 | Jun 23–Jun 30 | 62 | no-fit: Needs 100 days; Alamosa has 62 after Jun 23. | — |
| Eggplant | Apr 21 | Jun 23–Jun 30 | 55 | head-start: Even planted out Jun 23, the outdoor season is about 15 days short; choose an early variety or grow under cover. | — |
| Okra | May 12 | Jun 16–Jun 23 | 76 | fits: 55 days to maturity, 76 available after Jun 16. | Jun 23 |
| Basil | May 5 | Jun 30–Jun 30 | 62 | fits: 60 days to maturity, 62 available after Jun 30. | — |
| Cilantro | — | May 12–Jun 2 | 132 | two-plantings: Plant May 12 and again by Jul 19; both mature before Sep 21. | Jul 19 |
| Parsley | Mar 31 | Jun 16–Jun 23 | 97 | fits: 70 days to maturity, 97 available after Jun 16. | Jun 29 |
| Celery | Mar 31 | Jun 16–Jun 30 | 97 | no-fit: Needs 120 days; Alamosa has 97 after Jun 16. | — |
| Scallions | Mar 31 | May 12–May 26 | 146 | two-plantings: Plant May 12 and again by Jul 23; both mature before Oct 5. | Jul 23 |
| Turnip | — | May 12–May 26 | 146 | two-plantings: Plant May 12 and again by Aug 2; both mature before Oct 5. | Aug 2 |
| Kohlrabi | — | Apr 28–May 12 | 160 | two-plantings: Plant Apr 28 and again by Jul 28; both mature before Oct 5. | Jul 28 |
| Bok Choy | May 12 | Jun 2–Jun 9 | 111 | two-plantings: Plant Jun 2 and again by Jul 24; both mature before Sep 21. | Jul 24 |
| Collards | Mar 31 | May 12–May 26 | 146 | two-plantings: Plant May 12 and again by Jul 23; both mature before Oct 5. | Jul 23 |
| Cantaloupe | May 26 | Jun 23–Jun 30 | 55 | no-fit: Needs 85 days; Alamosa has 55 after Jun 23. | — |
| Chives | Mar 17 | Jun 16–Jun 23 | 111 | fits: 90 days to maturity, 111 available after Jun 16. | — |
| Dill | — | Apr 14–Jul 7 | 160 | two-plantings: Plant Apr 14 and again by Jul 14; both mature before Sep 21. | Jul 14 |
| Oregano | Mar 31 | Jun 16–Jun 23 | 111 | fits: 80 days to maturity, 111 available after Jun 16. | — |
| Rosemary | Mar 17 | Jun 16–Jun 23 | 97 | fits: 80 days to maturity, 97 available after Jun 16. | — |
| Sage | Apr 14 | Jun 16–Jun 23 | 111 | fits: 75 days to maturity, 111 available after Jun 16. | — |
| Thyme | Mar 31 | Jun 16–Jun 23 | 111 | fits: 90 days to maturity, 111 available after Jun 16. | — |
| Calendula | Apr 28 | May 26–Jun 9 | 118 | two-plantings: Plant May 26 and again by Jul 19; both mature before Sep 21. | Jul 19 |
| Cosmos | May 12 | Jun 9–Jun 23 | 83 | fits: 60 days to maturity, 83 available after Jun 9. | Jun 18 |
| Lavender | Mar 17 | Jun 9–Jun 23 | 118 | fits: 90 days to maturity, 118 available after Jun 9. | — |
| Marigolds | Apr 28 | Jun 9–Jun 16 | 83 | fits: 50 days to maturity, 83 available after Jun 9. | Jun 28 |
| Melons | May 26 | Jun 23–Jun 30 | 55 | no-fit: Needs 85 days; Alamosa has 55 after Jun 23. | — |
| Mint | — | Jun 9–Jun 23 | 118 | fits: 90 days to maturity, 118 available after Jun 9. | — |
| Nasturtiums | May 12 | Jun 9–Jun 16 | 83 | fits: 55 days to maturity, 83 available after Jun 9. | Jun 23 |
| Pole Beans | — | Jun 16–Jun 30 | 76 | fits: 65 days to maturity, 76 available after Jun 16. | — |
| Spaghetti Squash | May 26 | Jun 23–Jun 30 | 62 | no-fit: Needs 90 days; Alamosa has 62 after Jun 23. | — |
| Sunflowers | — | Jun 9–Jun 23 | 83 | fits: 70 days to maturity, 83 available after Jun 9. | — |
| Tomatillos | Apr 14 | Jun 16–Jun 23 | 62 | head-start: Even planted out Jun 16, the outdoor season is about 13 days short; choose an early variety or grow under cover. | — |
| Watermelon | May 26 | Jun 16–Jun 23 | 62 | head-start: Even planted out Jun 16, the outdoor season is about 18 days short; choose an early variety or grow under cover. | — |
| Yellow Squash | May 26 | Jun 23–Jun 30 | 69 | fits: 55 days to maturity, 69 available after Jun 23. | — |
| Zinnias | May 12 | Jun 9–Jun 23 | 83 | fits: 60 days to maturity, 83 available after Jun 9. | Jun 18 |
Month by month in Alamosa
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start the slowest-growing crops indoors: onions, leeks, and celery (10–12 weeks before last frost). |
| March | Start indoors: Chives (Mar 17), Lavender (Mar 17), Onion (Mar 17), Rosemary (Mar 17), Celery (Mar 31), Collards (Mar 31), +5 more. |
| April | Start indoors: Broccoli (Apr 14), Brussel Sprouts (Apr 14), Cabbage (Apr 14), Lettuce (Apr 14), Sage (Apr 14), Swiss Chard (Apr 14), +6 more. Direct sow from: Arugula (Apr 14), Beets (Apr 14), Dill (Apr 14), Peas (Apr 14), Radish (Apr 14), Spinach (Apr 14), +1 more. |
| May | Start indoors: Basil (May 5), Tomato (May 5), Bok Choy (May 12), Corn (May 12), Cosmos (May 12), Nasturtiums (May 12), +11 more. Direct sow from: Cilantro (May 12), Turnip (May 12), Carrots (May 19), Potatoes (May 26). Transplant from: Broccoli (May 12), Brussel Sprouts (May 12), Cabbage (May 12), Collards (May 12), Kale (May 12), Lettuce (May 12), +4 more. Plant: Strawberry (May 5). |
| June | Direct sow from: Sunflowers (Jun 9), Beans (Jun 16), Pole Beans (Jun 16). Transplant from: Bok Choy (Jun 2), Cauliflower (Jun 2), Cosmos (Jun 9), Lavender (Jun 9), Marigolds (Jun 9), Mint (Jun 9), +25 more. Last frost around June 9. Last sowing dates: Brussel Sprouts (Jun 13), Cosmos (Jun 18), Zinnias (Jun 18), Broccoli (Jun 19), Nasturtiums (Jun 23), Okra (Jun 23), +4 more. |
| July | Last sowing dates: Peas (Jul 4), Cabbage (Jul 13), Carrots (Jul 13), Beets (Jul 14), Dill (Jul 14), Swiss Chard (Jul 14), +8 more. |
| August | Last sowing dates: Turnip (Aug 2), Arugula (Aug 12), Spinach (Aug 12), Radish (Aug 13). |
| September | Direct sow from: Garlic (Sep 14). First frost around September 14. |
| October | Last sowing dates: Garlic (Oct 5). |
| 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 Alamosa, CO (ZIP 81101)?
The median last spring frost date for Alamosa, CO (ZIP code 81101) is around June 9. 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 May 24; one in ten it runs past June 23.
What is the first fall frost date in Alamosa, CO?
The median first fall frost date for Alamosa, CO is around September 14. 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 1 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Alamosa, CO?
The frost-free growing season in Alamosa is about 97 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 Alamosa (97 frost-free days, a short season), 29 of 56 planner crops fit outright, 14 get two plantings, 5 need an indoor start, 7 don't reliably mature, 1 crop is perennial.
What USDA hardiness zone is Alamosa, CO?
Alamosa, CO is in USDA hardiness zone 4b (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 Alamosa, CO?
Start tomatoes indoors May 5 and plant out Jun 23 in Alamosa. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Alamosa?
Two: plant May 12 and again by Jul 24; both mature before Sep 21.
When do I plant garlic in Alamosa?
Sep 14 to Oct 5; it overwinters and is ready the following summer.
Can I grow Celery in Alamosa?
Not reliably outdoors. Needs 120 days; Alamosa has 97 after Jun 16.
Which nearby ZIP has a longer season?
Pueblo (ZIP 81004) has 153 frost-free days, 56 more than Alamosa (ZIP 81101). See Pueblo ZIP 81004 frost dates
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