Frost dates for 55010Castle Rock, MN
The average last spring frost in Castle Rock is April 27 and the average first fall frost is October 10, giving a typical growing season of about 166 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 27
- Average first fall frost
- Oct 10
- Growing season
- 166 days
Safer after May 10 (1-in-10 risk)
Possible by Sep 27 (1-in-10 risk)
Last frost typically in 175 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) | Apr 23 · May 7 · May 21 | Sep 20 · Oct 2 · Oct 15 | 147 days | 100% |
| Frost / freeze (32°F) | Apr 12 · Apr 27 · May 10 | Sep 27 · Oct 10 · Oct 25 | 166 days | 100% |
| Hard freeze (28°F) | Apr 2 · Apr 15 · Apr 29 | Oct 7 · Oct 22 · Nov 5 | 189 days | 100% |
Planting calendar for Castle Rock
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 | Mar 27 – Jun 2 |
| Tomatoes | Transplant outdoors | May 13 – Jun 20 |
| Peppers | Start seeds indoors | Mar 27 – Apr 27 |
| Peppers | Transplant outdoors | May 27 – Jun 27 |
| Eggplant | Start seeds indoors | Apr 13 – May 12 |
| Eggplant | Transplant outdoors | May 27 – Jun 27 |
| Cucumbers | Sow outdoors | May 27 – Jun 30 |
| Summer squash | Sow outdoors | May 13 – Jun 27 |
| Winter squash & pumpkins | Sow outdoors | May 27 – Jun 27 |
| Snap beans | Sow outdoors | May 13 – Jul 23 |
| Sweet corn | Sow outdoors | May 13 – Jun 20 |
| Watermelon & cantaloupe | Sow outdoors | May 27 – Jun 27 |
| Okra | Sow outdoors | May 20 – Jun 12 |
| Peas | Sow outdoors (spring) | Mar 27 – May 12 |
| Potatoes | Plant outdoors (spring) | Mar 27 – May 27 |
| Onions | Start seeds indoors (spring) | Feb 13 – Mar 12 |
| Onions | Transplant outdoors (spring) | Apr 13 – May 12 |
| Broccoli | Start seeds indoors (spring) | Mar 9 – Apr 12 |
| Broccoli | Transplant outdoors (spring) | Apr 13 – May 12 |
| Broccoli | Start seeds indoors (fall) | Jun 10 – Jun 20 |
| Broccoli | Transplant outdoors (fall) | Jul 10 – Jul 21 |
| Cabbage | Start seeds indoors (spring) | Feb 27 – Mar 27 |
| Cabbage | Transplant outdoors (spring) | Mar 27 – Apr 27 |
| Cabbage | Start seeds indoors (fall) | May 31 – Jun 30 |
| Cabbage | Transplant outdoors (fall) | Jun 30 – Jul 31 |
| Leaf lettuce | Sow outdoors (spring) | Mar 27 – Jun 12 |
| Leaf lettuce | Sow outdoors (fall) | Jun 30 – Aug 16 |
| Spinach | Sow outdoors (spring) | Mar 20 – May 3 |
| Spinach | Sow outdoors (fall) | Jul 17 – Aug 21 |
| Radishes | Sow outdoors (spring) | Mar 27 – May 17 |
| Radishes | Sow outdoors (fall) | Jun 30 – Aug 31 |
| Kale | Sow outdoors (spring) | Apr 13 – May 3 |
| Kale | Sow outdoors (fall) | Jun 23 – Jul 31 |
| Carrots | Sow outdoors (spring) | Apr 27 – Jun 12 |
| Carrots | Sow outdoors (fall) | May 31 – Jul 16 |
| Garlic | Plant outdoors (fall) | Sep 30 – Oct 31 |
Where these dates come from
ZIP code 55010 is matched to the NOAA station Farmington 3 Nw, MN, 13.7 km away, at 980 ft elevation (45 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Farmington 3 Nw, MN (used) | 980 ft | Apr 27 | Oct 10 |
| Rosemount Rsch & Outreach Ctr, MN | 945 ft | May 2 | Oct 5 |
| Faribault, MN | 970 ft | May 5 | Oct 5 |
| Hastings Dam 2, MN | 680 ft | Apr 23 | Oct 19 |
Frost dates near Castle Rock
- Northfield, MN 55057 · last May 5, first Oct 5
- Randolph, MN 55065 · last Apr 27, first Oct 10
- Farmington, MN 55024 · last Apr 27, first Oct 10
- Elko New Market, MN 55020 · last Apr 27, first Oct 10
- Lakeville, MN 55044 · last Apr 27, first Oct 10
- Dundas, MN 55019 · last May 5, first Oct 5
- Hampton, MN 55031 · last May 2, first Oct 5
- Webster, MN 55088 · last May 5, first Oct 5
Frequently asked questions
- When is the last frost in Castle Rock, MN?
- For ZIP code 55010, the average last spring frost (32°F) is April 27, based on NOAA 1991-2020 climate normals for the Farmington 3 Nw, MN weather station. There is a 1-in-10 chance of a frost after May 10.
- When is the first frost in Castle Rock, MN?
- The average first fall frost (32°F) is October 10. There is a 1-in-10 chance of frost by September 27, so tender plants are at risk from that point on.
- How long is the growing season in 55010?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 166 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.