Frost dates for 80118Larkspur, CO
The average last spring frost in Larkspur is May 17 and the average first fall frost is October 1, giving a typical growing season of about 136 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- May 17
- Average first fall frost
- Oct 1
- Growing season
- 136 days
Safer after May 30 (1-in-10 risk)
Possible by Sep 19 (1-in-10 risk)
Last frost typically in 202 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | May 16 · May 29 · Jun 12 | Sep 9 · Sep 23 · Oct 2 | 116 days | 100% |
| Frost / freeze (32°F) | May 5 · May 17 · May 30 | Sep 19 · Oct 1 · Oct 12 | 136 days | 100% |
| Hard freeze (28°F) | Apr 26 · May 6 · May 20 | Sep 28 · Oct 9 · Oct 20 | 154 days | 100% |
Planting calendar for Larkspur
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Apr 16 – Jun 22 |
| Tomatoes | Transplant outdoors | Jun 2 – Jun 11 |
| Peppers | Start seeds indoors | Apr 16 – May 17 |
| Peppers | Transplant outdoors | Jun 16 – Jul 17 |
| Eggplant | Start seeds indoors | May 3 – Jun 1 |
| Eggplant | Transplant outdoors | Jun 16 – Jul 17 |
| Cucumbers | Sow outdoors | Jun 16 – Jun 21 |
| Summer squash | Sow outdoors | Jun 2 – Jul 17 |
| Winter squash & pumpkins | Sow outdoors | Jun 16 – Jul 17 |
| Snap beans | Sow outdoors | Jun 2 – Jul 14 |
| Sweet corn | Sow outdoors | Jun 2 – Jun 11 |
| Watermelon & cantaloupe | Sow outdoors | Jun 16 – Jul 17 |
| Okra | Sow outdoors | Jun 9 – Jul 2 |
| Peas | Sow outdoors (spring) | Apr 16 – Jun 1 |
| Potatoes | Plant outdoors (spring) | Apr 16 – Jun 16 |
| Onions | Start seeds indoors (spring) | Mar 5 – Apr 1 |
| Onions | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (spring) | Mar 29 – May 2 |
| Broccoli | Transplant outdoors (spring) | May 3 – Jun 1 |
| Broccoli | Start seeds indoors (fall) | Jun 1 – Jun 11 |
| Broccoli | Transplant outdoors (fall) | Jul 1 – Jul 12 |
| Cabbage | Start seeds indoors (spring) | Mar 19 – Apr 16 |
| Cabbage | Transplant outdoors (spring) | Apr 16 – May 17 |
| Cabbage | Start seeds indoors (fall) | May 22 – Jun 21 |
| Cabbage | Transplant outdoors (fall) | Jun 21 – Jul 22 |
| Leaf lettuce | Sow outdoors (spring) | Apr 16 – Jul 2 |
| Leaf lettuce | Sow outdoors (fall) | Jun 21 – Aug 7 |
| Spinach | Sow outdoors (spring) | Apr 9 – May 23 |
| Spinach | Sow outdoors (fall) | Jul 8 – Aug 12 |
| Radishes | Sow outdoors (spring) | Apr 16 – Jun 6 |
| Radishes | Sow outdoors (fall) | Jun 21 – Aug 22 |
| Kale | Sow outdoors (spring) | May 3 – May 23 |
| Kale | Sow outdoors (fall) | Jun 14 – Jul 22 |
| Carrots | Sow outdoors (spring) | May 17 – Jul 2 |
| Carrots | Sow outdoors (fall) | May 22 – Jul 7 |
| Garlic | Plant outdoors (fall) | Sep 21 – Oct 22 |
Where these dates come from
ZIP code 80118 is matched to the NOAA station Monument 3S, CO, 16.1 km away, at 6,821 ft elevation (26 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Monument 3S, CO (used) | 6,821 ft | May 17 | Oct 1 |
| Monument, CO | 7,080 ft | May 14 | Oct 1 |
| Black Forest 6Wnw, CO | 6,957 ft | May 11 | Oct 6 |
| Castle Rock, CO | 6,185 ft | May 9 | Oct 2 |
Frost dates near Larkspur
- Palmer Lake, CO 80133 · last May 14, first Oct 1
- Monument, CO 80132 · last May 14, first Oct 1
- Colorado Springs, CO 80921 · last May 14, first Oct 1
- Castle Rock, CO 80109 · last May 16, first Oct 2
- Littleton, CO 80163 · last May 9, first Oct 2
- Sedalia, CO 80135 · last May 17, first Oct 1
- Franktown, CO 80116 · last May 9, first Oct 2
- Elbert, CO 80106 · last May 29, first Sep 21
Frequently asked questions
- When is the last frost in Larkspur, CO?
- For ZIP code 80118, the average last spring frost (32°F) is May 17, based on NOAA 1991-2020 climate normals for the Monument 3S, CO weather station. There is a 1-in-10 chance of a frost after May 30.
- When is the first frost in Larkspur, CO?
- The average first fall frost (32°F) is October 1. There is a 1-in-10 chance of frost by September 19, so tender plants are at risk from that point on.
- How long is the growing season in 80118?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 136 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.