Frost Dates for Morrison, CO 80465
Last spring frost May 13 · First fall frost September 29 · 139 frost-free days · USDA Zone 5b
ZIP 80465 has about 16,600 people.
Moderate season: 139 frost-free days. Spring frost risk spans April 27–May 28 (31 days). Fall frost risk spans September 15–October 12 (27 days).
Frost probability for 80465
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 28 | May 13 | April 27 |
| Fall (first frost) | September 15 | September 29 | October 12 |
Dates come from NOAA 1971–2000 freeze probabilities at KASSLER (16.4 km away); the 50% date is the median year.
Which crops fit a 139-day season in Morrison
In Morrison (139 frost-free days, a moderate season), 38 of 56 planner crops fit outright, 17 get two plantings, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Apr 8 | May 27–Jun 3 | 97 | fits: 80 days to maturity, 97 available after May 27. | May 30 |
| Pepper | Apr 1 | May 27–Jun 3 | 97 | fits: 75 days to maturity, 97 available after May 27. | Jun 4 |
| Lettuce | Mar 18 | Apr 15–Apr 22 | 174 | two-plantings: Plant Apr 15 and again by Aug 8; both mature before Oct 6. | Aug 8 |
| Carrots | — | Apr 22–Apr 29 | 181 | fits: 70 days to maturity, 181 available after Apr 22. | Jul 28 |
| Cucumber | Apr 22 | May 27–Jun 3 | 111 | fits: 60 days to maturity, 111 available after May 27. | Jul 3 |
| Beans | — | May 20–Jun 3 | 125 | fits: 60 days to maturity, 125 available after May 20. | Jul 10 |
| Peas | — | Mar 18–May 27 | 202 | fits: 65 days to maturity, 202 available after Mar 18. | Jul 19 |
| Zucchini | Apr 29 | May 27–Jun 3 | 111 | fits: 55 days to maturity, 111 available after May 27. | Jul 8 |
| Onion | Feb 18 | Apr 15–Apr 29 | 174 | fits: 100 days to maturity, 174 available after Apr 15. | — |
| Spinach | — | Mar 18–May 6 | 216 | two-plantings: Plant Mar 18 and again by Aug 27; both mature before Oct 20. | Aug 27 |
| Kale | Mar 4 | Apr 15–Apr 29 | 188 | two-plantings: Plant Apr 15 and again by Aug 12; both mature before Oct 20. | Aug 12 |
| Broccoli | Mar 18 | Apr 15–Apr 29 | 174 | fits: 80 days to maturity, 174 available after Apr 15. | Jul 4 |
| Cabbage | Mar 18 | Apr 15–Apr 29 | 188 | fits: 70 days to maturity, 188 available after Apr 15. | Jul 28 |
| Radish | — | Mar 18–Jun 10 | 202 | two-plantings: Plant Mar 18 and again by Aug 28; both mature before Oct 6. | Aug 28 |
| Beets | — | Mar 18–Jun 10 | 202 | two-plantings: Plant Mar 18 and again by Jul 29; both mature before Oct 6. | Jul 29 |
| Potatoes | — | Apr 29–May 6 | 160 | fits: 90 days to maturity, 160 available after Apr 29. | — |
| Garlic | — | Sep 29 | 244 | overwinter: Plant Sep 29 to Oct 20; harvest the following summer. | Oct 20 |
| Strawberry | — | Apr 8–Jun 3 | 195 | perennial: A perennial: plant Apr 8; it fruits from the following year and keeps producing for several years. | — |
| Corn | Apr 15 | May 20–May 27 | 111 | fits: 75 days to maturity, 111 available after May 20. | Jun 11 |
| Pumpkin | Apr 29 | May 27–May 27 | 104 | fits: 100 days to maturity, 104 available after May 27. | — |
| Cauliflower | Apr 1 | May 6–May 20 | 153 | fits: 75 days to maturity, 153 available after May 6. | Jul 9 |
| Swiss Chard | Mar 18 | Apr 29–Apr 29 | 160 | two-plantings: Plant Apr 29 and again by Jul 29; both mature before Oct 6. | Jul 29 |
| Arugula | — | Mar 18–Jun 10 | 216 | two-plantings: Plant Mar 18 and again by Aug 27; both mature before Oct 20. | Aug 27 |
| Brussel Sprouts | Mar 18 | Apr 15–Apr 29 | 188 | fits: 100 days to maturity, 188 available after Apr 15. | Jun 28 |
| Butternut Squash | Apr 29 | May 27–Jun 3 | 104 | fits: 100 days to maturity, 104 available after May 27. | — |
| Eggplant | Mar 25 | May 27–Jun 3 | 97 | fits: 70 days to maturity, 97 available after May 27. | Jun 9 |
| Okra | Apr 15 | May 20–May 27 | 118 | fits: 55 days to maturity, 118 available after May 20. | Jul 8 |
| Basil | Apr 8 | Jun 3–Jun 3 | 104 | fits: 60 days to maturity, 104 available after Jun 3. | Jul 3 |
| Cilantro | — | Apr 15–May 6 | 174 | two-plantings: Plant Apr 15 and again by Aug 3; both mature before Oct 6. | Aug 3 |
| Parsley | Mar 4 | May 20–May 27 | 139 | fits: 70 days to maturity, 139 available after May 20. | Jul 14 |
| Celery | Mar 4 | May 20–Jun 3 | 139 | fits: 120 days to maturity, 139 available after May 20. | May 25 |
| Scallions | Mar 4 | Apr 15–Apr 29 | 188 | two-plantings: Plant Apr 15 and again by Aug 7; both mature before Oct 20. | Aug 7 |
| Turnip | — | Apr 15–Apr 29 | 188 | two-plantings: Plant Apr 15 and again by Aug 17; both mature before Oct 20. | Aug 17 |
| Kohlrabi | — | Apr 1–Apr 15 | 202 | two-plantings: Plant Apr 1 and again by Aug 12; both mature before Oct 20. | Aug 12 |
| Bok Choy | Apr 15 | May 6–May 13 | 153 | two-plantings: Plant May 6 and again by Aug 8; both mature before Oct 6. | Aug 8 |
| Collards | Mar 4 | Apr 15–Apr 29 | 188 | two-plantings: Plant Apr 15 and again by Aug 7; both mature before Oct 20. | Aug 7 |
| Cantaloupe | Apr 29 | May 27–Jun 3 | 97 | fits: 85 days to maturity, 97 available after May 27. | — |
| Chives | Feb 18 | May 20–May 27 | 153 | fits: 90 days to maturity, 153 available after May 20. | — |
| Dill | — | Mar 18–Jun 10 | 202 | two-plantings: Plant Mar 18 and again by Jul 29; both mature before Oct 6. | Jul 29 |
| Oregano | Mar 4 | May 20–May 27 | 153 | fits: 80 days to maturity, 153 available after May 20. | — |
| Rosemary | Feb 18 | May 20–May 27 | 139 | fits: 80 days to maturity, 139 available after May 20. | — |
| Sage | Mar 18 | May 20–May 27 | 153 | fits: 75 days to maturity, 153 available after May 20. | — |
| Thyme | Mar 4 | May 20–May 27 | 153 | fits: 90 days to maturity, 153 available after May 20. | — |
| Calendula | Apr 1 | Apr 29–May 13 | 160 | two-plantings: Plant Apr 29 and again by Aug 3; both mature before Oct 6. | Aug 3 |
| Cosmos | Apr 15 | May 13–May 27 | 125 | fits: 60 days to maturity, 125 available after May 13. | Jul 3 |
| Lavender | Feb 18 | May 13–May 27 | 160 | fits: 90 days to maturity, 160 available after May 13. | — |
| Marigolds | Apr 1 | May 13–May 20 | 125 | two-plantings: Plant May 13 and again by Jul 13; both mature before Sep 15. | Jul 13 |
| Melons | Apr 29 | May 27–Jun 3 | 97 | fits: 85 days to maturity, 97 available after May 27. | — |
| Mint | — | May 13–May 27 | 160 | fits: 90 days to maturity, 160 available after May 13. | — |
| Nasturtiums | Apr 15 | May 13–May 20 | 125 | two-plantings: Plant May 13 and again by Jul 8; both mature before Sep 15. | Jul 8 |
| Pole Beans | — | May 20–Jun 3 | 118 | fits: 65 days to maturity, 118 available after May 20. | Jun 28 |
| Spaghetti Squash | Apr 29 | May 27–Jun 3 | 104 | fits: 90 days to maturity, 104 available after May 27. | — |
| Sunflowers | — | May 13–May 27 | 125 | fits: 70 days to maturity, 125 available after May 13. | Jun 23 |
| Tomatillos | Mar 18 | May 20–May 27 | 104 | fits: 75 days to maturity, 104 available after May 20. | Jun 4 |
| Watermelon | Apr 29 | May 20–May 27 | 104 | fits: 80 days to maturity, 104 available after May 20. | May 30 |
| Yellow Squash | Apr 29 | May 27–Jun 3 | 111 | fits: 55 days to maturity, 111 available after May 27. | Jul 8 |
| Zinnias | Apr 15 | May 13–May 27 | 125 | fits: 60 days to maturity, 125 available after May 13. | Jul 3 |
Month by month in Morrison
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start indoors: Chives (Feb 18), Lavender (Feb 18), Onion (Feb 18), Rosemary (Feb 18). |
| March | Start indoors: Celery (Mar 4), Collards (Mar 4), Kale (Mar 4), Oregano (Mar 4), Parsley (Mar 4), Scallions (Mar 4), +9 more. Direct sow from: Arugula (Mar 18), Beets (Mar 18), Dill (Mar 18), Peas (Mar 18), Radish (Mar 18), Spinach (Mar 18). |
| April | Start indoors: Calendula (Apr 1), Cauliflower (Apr 1), Marigolds (Apr 1), Pepper (Apr 1), Basil (Apr 8), Tomato (Apr 8), +15 more. Direct sow from: Kohlrabi (Apr 1), Cilantro (Apr 15), Turnip (Apr 15), Carrots (Apr 22), Potatoes (Apr 29). Transplant from: Broccoli (Apr 15), Brussel Sprouts (Apr 15), Cabbage (Apr 15), Collards (Apr 15), Kale (Apr 15), Lettuce (Apr 15), +4 more. Plant: Strawberry (Apr 8). |
| May | Direct sow from: Sunflowers (May 13), Beans (May 20), Pole Beans (May 20). Transplant from: Bok Choy (May 6), Cauliflower (May 6), Cosmos (May 13), Lavender (May 13), Marigolds (May 13), Mint (May 13), +24 more. Last frost around May 13. Last sowing dates: Celery (May 25), Tomato (May 30), Watermelon (May 30). |
| June | Transplant from: Basil (Jun 3). Last sowing dates: Pepper (Jun 4), Tomatillos (Jun 4), Eggplant (Jun 9), Corn (Jun 11), Sunflowers (Jun 23), Brussel Sprouts (Jun 28), +1 more. |
| July | Last sowing dates: Basil (Jul 3), Cosmos (Jul 3), Cucumber (Jul 3), Zinnias (Jul 3), Broccoli (Jul 4), Nasturtiums (Jul 8), +13 more. |
| August | Last sowing dates: Calendula (Aug 3), Cilantro (Aug 3), Collards (Aug 7), Scallions (Aug 7), Bok Choy (Aug 8), Lettuce (Aug 8), +6 more. |
| September | Direct sow from: Garlic (Sep 29). First frost around September 29. |
| October | Last sowing dates: Garlic (Oct 20). |
| 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 Morrison, CO (ZIP 80465)?
The median last spring frost date for Morrison, CO (ZIP code 80465) is around May 13. 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 27; one in ten it runs past May 28.
What is the first fall frost date in Morrison, CO?
The median first fall frost date for Morrison, CO is around September 29. 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 15 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Morrison, CO?
The frost-free growing season in Morrison is about 139 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 Morrison (139 frost-free days, a moderate season), 38 of 56 planner crops fit outright, 17 get two plantings, 1 crop is perennial.
What USDA hardiness zone is Morrison, CO?
Morrison, 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 Morrison, CO?
Start tomatoes indoors Apr 8 and plant out May 27 in Morrison. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Morrison?
Two: plant Apr 15 and again by Aug 8; both mature before Oct 6.
When do I plant garlic in Morrison?
Sep 29 to Oct 20; it overwinters and is ready the following summer.
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