Frost Dates for Fort Lupton, CO 80621
Last spring frost May 2 · First fall frost October 1 · 152 frost-free days · USDA Zone 5b
ZIP 80621 has about 15,100 people.
Moderate season: 152 frost-free days. Spring frost risk spans April 21–May 13 (22 days). Fall frost risk spans September 17–October 14 (27 days).
Frost probability for 80621
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 13 | May 2 | April 21 |
| Fall (first frost) | September 17 | October 1 | October 14 |
Dates come from NOAA 1971–2000 freeze probabilities at GREELEY UNC (33.9 km away); the 50% date is the median year.
Which crops fit a 152-day season in Fort Lupton
In Fort Lupton (152 frost-free days, a moderate season), 32 of 56 planner crops fit outright, 23 get two plantings, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Mar 28 | May 16–May 23 | 110 | fits: 80 days to maturity, 110 available after May 16. | Jun 1 |
| Pepper | Mar 21 | May 16–May 23 | 110 | fits: 75 days to maturity, 110 available after May 16. | Jun 6 |
| Lettuce | Mar 7 | Apr 4–Apr 11 | 187 | two-plantings: Plant Apr 4 and again by Aug 10; both mature before Oct 8. | Aug 10 |
| Carrots | — | Apr 11–Apr 18 | 194 | fits: 70 days to maturity, 194 available after Apr 11. | Jul 30 |
| Cucumber | Apr 11 | May 16–May 23 | 124 | fits: 60 days to maturity, 124 available after May 16. | Jul 5 |
| Beans | — | May 9–May 23 | 138 | two-plantings: Plant May 9 and again by Jul 12; both mature before Sep 24. | Jul 12 |
| Peas | — | Mar 7–May 16 | 215 | fits: 65 days to maturity, 215 available after Mar 7. | Jul 21 |
| Zucchini | Apr 18 | May 16–May 23 | 124 | two-plantings: Plant May 16 and again by Jul 10; both mature before Sep 17. | Jul 10 |
| Onion | Feb 7 | Apr 4–Apr 18 | 187 | fits: 100 days to maturity, 187 available after Apr 4. | — |
| Spinach | — | Mar 7–Apr 25 | 229 | two-plantings: Plant Mar 7 and again by Aug 29; both mature before Oct 22. | Aug 29 |
| Kale | Feb 21 | Apr 4–Apr 18 | 201 | two-plantings: Plant Apr 4 and again by Aug 14; both mature before Oct 22. | Aug 14 |
| Broccoli | Mar 7 | Apr 4–Apr 18 | 187 | fits: 80 days to maturity, 187 available after Apr 4. | Jul 6 |
| Cabbage | Mar 7 | Apr 4–Apr 18 | 201 | fits: 70 days to maturity, 201 available after Apr 4. | Jul 30 |
| Radish | — | Mar 7–May 30 | 215 | two-plantings: Plant Mar 7 and again by Aug 30; both mature before Oct 8. | Aug 30 |
| Beets | — | Mar 7–May 30 | 215 | two-plantings: Plant Mar 7 and again by Jul 31; both mature before Oct 8. | Jul 31 |
| Potatoes | — | Apr 18–Apr 25 | 173 | fits: 90 days to maturity, 173 available after Apr 18. | — |
| Garlic | — | Oct 1 | 257 | overwinter: Plant Oct 1 to Oct 22; harvest the following summer. | Oct 22 |
| Strawberry | — | Mar 28–May 23 | 208 | perennial: A perennial: plant Mar 28; it fruits from the following year and keeps producing for several years. | — |
| Corn | Apr 4 | May 9–May 16 | 124 | fits: 75 days to maturity, 124 available after May 9. | Jun 13 |
| Pumpkin | Apr 18 | May 16–May 16 | 117 | fits: 100 days to maturity, 117 available after May 16. | May 19 |
| Cauliflower | Mar 21 | Apr 25–May 9 | 166 | fits: 75 days to maturity, 166 available after Apr 25. | Jul 11 |
| Swiss Chard | Mar 7 | Apr 18–Apr 18 | 173 | two-plantings: Plant Apr 18 and again by Jul 31; both mature before Oct 8. | Jul 31 |
| Arugula | — | Mar 7–May 30 | 229 | two-plantings: Plant Mar 7 and again by Aug 29; both mature before Oct 22. | Aug 29 |
| Brussel Sprouts | Mar 7 | Apr 4–Apr 18 | 201 | fits: 100 days to maturity, 201 available after Apr 4. | Jun 30 |
| Butternut Squash | Apr 18 | May 16–May 23 | 117 | fits: 100 days to maturity, 117 available after May 16. | May 19 |
| Eggplant | Mar 14 | May 16–May 23 | 110 | fits: 70 days to maturity, 110 available after May 16. | Jun 11 |
| Okra | Apr 4 | May 9–May 16 | 131 | two-plantings: Plant May 9 and again by Jul 10; both mature before Sep 17. | Jul 10 |
| Basil | Mar 28 | May 23–May 23 | 117 | fits: 60 days to maturity, 117 available after May 23. | Jul 5 |
| Cilantro | — | Apr 4–Apr 25 | 187 | two-plantings: Plant Apr 4 and again by Aug 5; both mature before Oct 8. | Aug 5 |
| Parsley | Feb 21 | May 9–May 16 | 152 | fits: 70 days to maturity, 152 available after May 9. | Jul 16 |
| Celery | Feb 21 | May 9–May 23 | 152 | fits: 120 days to maturity, 152 available after May 9. | May 27 |
| Scallions | Feb 21 | Apr 4–Apr 18 | 201 | two-plantings: Plant Apr 4 and again by Aug 9; both mature before Oct 22. | Aug 9 |
| Turnip | — | Apr 4–Apr 18 | 201 | two-plantings: Plant Apr 4 and again by Aug 19; both mature before Oct 22. | Aug 19 |
| Kohlrabi | — | Mar 21–Apr 4 | 215 | two-plantings: Plant Mar 21 and again by Aug 14; both mature before Oct 22. | Aug 14 |
| Bok Choy | Apr 4 | Apr 25–May 2 | 166 | two-plantings: Plant Apr 25 and again by Aug 10; both mature before Oct 8. | Aug 10 |
| Collards | Feb 21 | Apr 4–Apr 18 | 201 | two-plantings: Plant Apr 4 and again by Aug 9; both mature before Oct 22. | Aug 9 |
| Cantaloupe | Apr 18 | May 16–May 23 | 110 | fits: 85 days to maturity, 110 available after May 16. | May 27 |
| Chives | Feb 7 | May 9–May 16 | 166 | fits: 90 days to maturity, 166 available after May 9. | — |
| Dill | — | Mar 7–May 30 | 215 | two-plantings: Plant Mar 7 and again by Jul 31; both mature before Oct 8. | Jul 31 |
| Oregano | Feb 21 | May 9–May 16 | 166 | fits: 80 days to maturity, 166 available after May 9. | — |
| Rosemary | Feb 7 | May 9–May 16 | 152 | fits: 80 days to maturity, 152 available after May 9. | — |
| Sage | Mar 7 | May 9–May 16 | 166 | fits: 75 days to maturity, 166 available after May 9. | — |
| Thyme | Feb 21 | May 9–May 16 | 166 | fits: 90 days to maturity, 166 available after May 9. | — |
| Calendula | Mar 21 | Apr 18–May 2 | 173 | two-plantings: Plant Apr 18 and again by Aug 5; both mature before Oct 8. | Aug 5 |
| Cosmos | Apr 4 | May 2–May 16 | 138 | two-plantings: Plant May 2 and again by Jul 5; both mature before Sep 17. | Jul 5 |
| Lavender | Feb 7 | May 2–May 16 | 173 | fits: 90 days to maturity, 173 available after May 2. | — |
| Marigolds | Mar 21 | May 2–May 9 | 138 | two-plantings: Plant May 2 and again by Jul 15; both mature before Sep 17. | Jul 15 |
| Melons | Apr 18 | May 16–May 23 | 110 | fits: 85 days to maturity, 110 available after May 16. | May 27 |
| Mint | — | May 2–May 16 | 173 | fits: 90 days to maturity, 173 available after May 2. | — |
| Nasturtiums | Apr 4 | May 2–May 9 | 138 | two-plantings: Plant May 2 and again by Jul 10; both mature before Sep 17. | Jul 10 |
| Pole Beans | — | May 9–May 23 | 131 | fits: 65 days to maturity, 131 available after May 9. | Jun 30 |
| Spaghetti Squash | Apr 18 | May 16–May 23 | 117 | fits: 90 days to maturity, 117 available after May 16. | May 29 |
| Sunflowers | — | May 2–May 16 | 138 | fits: 70 days to maturity, 138 available after May 2. | Jun 25 |
| Tomatillos | Mar 7 | May 9–May 16 | 117 | fits: 75 days to maturity, 117 available after May 9. | Jun 6 |
| Watermelon | Apr 18 | May 9–May 16 | 117 | fits: 80 days to maturity, 117 available after May 9. | Jun 1 |
| Yellow Squash | Apr 18 | May 16–May 23 | 124 | two-plantings: Plant May 16 and again by Jul 10; both mature before Sep 17. | Jul 10 |
| Zinnias | Apr 4 | May 2–May 16 | 138 | two-plantings: Plant May 2 and again by Jul 5; both mature before Sep 17. | Jul 5 |
Month by month in Fort Lupton
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start indoors: Chives (Feb 7), Lavender (Feb 7), Onion (Feb 7), Rosemary (Feb 7), Celery (Feb 21), Collards (Feb 21), +5 more. |
| March | Start indoors: Broccoli (Mar 7), Brussel Sprouts (Mar 7), Cabbage (Mar 7), Lettuce (Mar 7), Sage (Mar 7), Swiss Chard (Mar 7), +8 more. Direct sow from: Arugula (Mar 7), Beets (Mar 7), Dill (Mar 7), Peas (Mar 7), Radish (Mar 7), Spinach (Mar 7), +1 more. Plant: Strawberry (Mar 28). |
| April | Start indoors: Bok Choy (Apr 4), Corn (Apr 4), Cosmos (Apr 4), Nasturtiums (Apr 4), Okra (Apr 4), Zinnias (Apr 4), +9 more. Direct sow from: Cilantro (Apr 4), Turnip (Apr 4), Carrots (Apr 11), Potatoes (Apr 18). Transplant from: Broccoli (Apr 4), Brussel Sprouts (Apr 4), Cabbage (Apr 4), Collards (Apr 4), Kale (Apr 4), Lettuce (Apr 4), +6 more. |
| May | Direct sow from: Sunflowers (May 2), Beans (May 9), Pole Beans (May 9). Transplant from: Cosmos (May 2), Lavender (May 2), Marigolds (May 2), Mint (May 2), Nasturtiums (May 2), Zinnias (May 2), +23 more. Last frost around May 2. Last sowing dates: Butternut Squash (May 19), Pumpkin (May 19), Cantaloupe (May 27), Celery (May 27), Melons (May 27), Spaghetti Squash (May 29). |
| June | Last sowing dates: Tomato (Jun 1), Watermelon (Jun 1), Pepper (Jun 6), Tomatillos (Jun 6), Eggplant (Jun 11), Corn (Jun 13), +3 more. |
| July | Last sowing dates: Basil (Jul 5), Cosmos (Jul 5), Cucumber (Jul 5), Zinnias (Jul 5), Broccoli (Jul 6), Nasturtiums (Jul 10), +13 more. |
| August | Last sowing dates: Calendula (Aug 5), Cilantro (Aug 5), Collards (Aug 9), Scallions (Aug 9), Bok Choy (Aug 10), Lettuce (Aug 10), +6 more. |
| September | First fall frost approaching (around October 1). Transplant fall brassicas. Sow spinach, arugula, and radishes. |
| October | Direct sow from: Garlic (Oct 1). First frost around October 1. Last sowing dates: Garlic (Oct 22). |
| November | Harvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year. |
| 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 Fort Lupton, CO (ZIP 80621)?
The median last spring frost date for Fort Lupton, CO (ZIP code 80621) is around May 2. 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 21; one in ten it runs past May 13.
What is the first fall frost date in Fort Lupton, CO?
The median first fall frost date for Fort Lupton, CO is around October 1. 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 17 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Fort Lupton, CO?
The frost-free growing season in Fort Lupton is about 152 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 Fort Lupton (152 frost-free days, a moderate season), 32 of 56 planner crops fit outright, 23 get two plantings, 1 crop is perennial.
What USDA hardiness zone is Fort Lupton, CO?
Fort Lupton, 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 Fort Lupton, CO?
Start tomatoes indoors Mar 28 and plant out May 16 in Fort Lupton. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Fort Lupton?
Two: plant Apr 4 and again by Aug 10; both mature before Oct 8.
When do I plant garlic in Fort Lupton?
Oct 1 to Oct 22; it overwinters and is ready the following summer.
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