Castle Rock, MN frost dates
Last spring frostApr 27median date
First fall frostOct 10median date
Growing season166 daysfrost-free
Hardiness zone4bZone 4b
How Castle Rock compares
- In 8 years out of 10, the last spring frost in Castle Rock falls between April 12 and May 10, a 28-day window. The first fall frost falls between September 27 and October 25.
- The median last frost is 8 days earlier than the Minnesota median of May 5.
- Its 166-day growing season is longer than 92% of the 801 Minnesota places with a regular frost season (state median 151 days).
- The last frost is 11 days earlier than the zone 4b median of May 8. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 4b chart.
- The weather station records an average of 150 nights a year at or below 32°F.
- Castle Rock shares its weather station with Lakeville, MN, 16 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 12 |
| 50% (median) | April 27 |
| 10% (safe for tender plants) | May 10 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 27 |
| 50% (median) | October 10 |
| 90% (late) | October 25 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Castle Rock, MN
Castle Rock, MN frost dates — last frost Apr 27, first frost Oct 10, zone 4b. whenisthelastfrost.com
Crop
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Start indoors: Feb 2 to Feb 16Transplant outside: Mar 30 to Apr 13
Start indoors: Feb 16 to Mar 2Transplant outside: May 11 to May 25
Start indoors: Feb 16 to Mar 2Transplant outside: May 11 to May 25
Start indoors: Mar 2 to Mar 16Transplant outside: May 4 to May 18
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 6 to Apr 20Sow outdoors: Mar 30 to May 4Plant for fall: Aug 15 to Sep 12
Start indoors: Mar 2 to Mar 16Transplant outside: Mar 30 to Apr 13Sow outdoors: Mar 30 to Apr 13Plant for fall: Aug 1 to Aug 22
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 13 to Apr 27Plant for fall: Jul 4 to Jul 25
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 6 to Apr 20Plant for fall: Jul 4 to Jul 25
Start indoors: Mar 2 to Mar 16Transplant outside: Apr 13 to Apr 27Plant for fall: Jul 4 to Jul 25
Start indoors: Mar 16 to Mar 30Transplant outside: May 18 to Jun 1Sow outdoors: May 18 to Jun 1
Start indoors: Mar 16 to Mar 30Transplant outside: May 4 to May 18
Sow outdoors: Mar 16 to Apr 6Plant for fall: Jul 18 to Aug 8
Sow outdoors: Mar 16 to Apr 6Plant for fall: Aug 15 to Sep 5
Sow outdoors: Mar 23 to May 4Plant for fall: Aug 29 to Sep 19
Start indoors: Mar 30 to Apr 6Transplant outside: May 11 to May 18Sow outdoors: May 4 to May 18Plant for fall: Jul 25 to Aug 8
Start indoors: Mar 30 to Apr 6Sow outdoors: May 4 to May 18Plant for fall: Aug 1 to Aug 15
Start indoors: Mar 30 to Apr 6Sow outdoors: May 4 to May 18
Start indoors: Mar 30 to Apr 6Transplant outside: May 11 to May 25
Sow outdoors: Apr 6 to May 4Plant for fall: Jul 18 to Aug 1
Sow outdoors: Apr 6 to May 4Plant for fall: Aug 1 to Aug 15
Sow outdoors: Apr 6 to Apr 27
Sow outdoors: Apr 13 to May 11Plant for fall: Aug 1 to Aug 15
Sow outdoors: Apr 13 to May 4Plant for fall: Aug 15 to Sep 5
Sow outdoors: May 4 to May 25Plant for fall: Jul 25 to Aug 8
Sow outdoors: May 4 to May 18
Transplant outside: May 11 to Jun 1
Plant for fall: Sep 26 to Oct 31
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Castle Rock, MN
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 2 – Feb 16 | Mar 30 – Apr 13 | — | — |
| Peppers | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Eggplant | Feb 16 – Mar 2 | May 11 – May 25 | — | — |
| Tomatoes | Mar 2 – Mar 16 | May 4 – May 18 | — | — |
| Lettuce | Mar 2 – Mar 16 | Apr 6 – Apr 20 | Mar 30 – May 4 | Aug 15 – Sep 12 |
| Kale | Mar 2 – Mar 16 | Mar 30 – Apr 13 | Mar 30 – Apr 13 | Aug 1 – Aug 22 |
| Broccoli | Mar 2 – Mar 16 | Apr 13 – Apr 27 | — | Jul 4 – Jul 25 |
| Cabbage | Mar 2 – Mar 16 | Apr 6 – Apr 20 | — | Jul 4 – Jul 25 |
| Cauliflower | Mar 2 – Mar 16 | Apr 13 – Apr 27 | — | Jul 4 – Jul 25 |
| Okra | Mar 16 – Mar 30 | May 18 – Jun 1 | May 18 – Jun 1 | — |
| Basil | Mar 16 – Mar 30 | May 4 – May 18 | — | — |
| Peas | — | — | Mar 16 – Apr 6 | Jul 18 – Aug 8 |
| Spinach | — | — | Mar 16 – Apr 6 | Aug 15 – Sep 5 |
| Radishes | — | — | Mar 23 – May 4 | Aug 29 – Sep 19 |
| Cucumbers | Mar 30 – Apr 6 | May 11 – May 18 | May 4 – May 18 | Jul 25 – Aug 8 |
| Zucchini & Summer Squash | Mar 30 – Apr 6 | — | May 4 – May 18 | Aug 1 – Aug 15 |
| Winter Squash & Pumpkins | Mar 30 – Apr 6 | — | May 4 – May 18 | — |
| Melons & Watermelon | Mar 30 – Apr 6 | May 11 – May 25 | — | — |
| Carrots | — | — | Apr 6 – May 4 | Jul 18 – Aug 1 |
| Beets | — | — | Apr 6 – May 4 | Aug 1 – Aug 15 |
| Potatoes | — | — | Apr 6 – Apr 27 | — |
| Swiss Chard | — | — | Apr 13 – May 11 | Aug 1 – Aug 15 |
| Cilantro | — | — | Apr 13 – May 4 | Aug 15 – Sep 5 |
| Green Beans | — | — | May 4 – May 25 | Jul 25 – Aug 8 |
| Sweet Corn | — | — | May 4 – May 18 | — |
| Sweet Potatoes | — | May 11 – Jun 1 | — | — |
| Garlic | — | — | — | Sep 26 – Oct 31 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Farmington 3 Nw, MN weather station, 14 km away (elevation 981 ft (299 m)).
Frost dates near Castle Rock
- Northfield May 5 · Oct 5
- Randolph Apr 27 · Oct 10
- Farmington Apr 27 · Oct 10
- Elko New Market Apr 27 · Oct 10
- Lakeville Apr 27 · Oct 10
- Dundas May 5 · Oct 5
- Hampton May 2 · Oct 5
- Webster May 5 · Oct 5
- Vermillion May 2 · Oct 5
- Dennison May 9 · Sep 30
Frequently asked questions
When is the last frost in Castle Rock, MN?
The median last spring frost in Castle Rock, MN is April 27. There is still about a 10% chance of frost after May 10, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Castle Rock, MN?
The median first fall frost is October 10, with about a 10% chance of frost before September 27.
How long is the growing season in Castle Rock, MN?
About 166 days between the median last spring frost and first fall frost.
What planting zone is Castle Rock, MN?
Castle Rock, MN is in USDA hardiness zone 4b.