When to plant sweet corn in zone 4b
In zone 4b, where the last spring frost typically comes around May 8, sow outdoors May 8 to 22.
The zone 4b schedule for sweet corn
- Sow outdoors
- May 8 to 22
- Safest planting date (10% frost risk)
- May 22
- First harvest, roughly
- July 7 to August 30
From the median frost dates of the NOAA stations assigned to the 1,164 ZIP codes in zone 4b, and the timing recommended by Cooperative Extension guides for sweet corn.
Frost risk in zone 4b
Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 4b, the typical last frost ranges from about May 1 in the earliest tenth of ZIP codes to May 25 in the latest tenth, and the first fall frost from September 22 to October 8. For a typical place in the zone:
- April 26Risky: a later frost happens in 9 years out of 10
- May 8Typical: frost after this date in half of years
- May 22Safe: a later frost only 1 year in 10
Sweet Corn are killed by frost, so if you want to be safe, plant out after the safe date rather than the typical one, or be ready to cover plants on a cold night.
Your dates for sweet corn
Set your ZIP code at the top of the page and we will work out when to plant sweet corn where you live, from the frost records of the nearest NOAA weather station. Your ZIP code is remembered on this device only.
Sweet Corn in zone 4b cities
| City | Typical last frost | Plant | Fall |
|---|---|---|---|
| Rochester, MN | Apr 30 | Apr 30 to May 14 | — |
| Duluth, MN | May 6 | May 19 to Jun 2 | — |
| Lakeville, MN | May 2 | May 2 to 16 | — |
| St. Cloud, MN | May 7 | May 7 to 21 | — |
| Eau Claire, WI | May 8 | May 8 to 22 | — |
| Great Falls, MT | May 19 | May 19 to Jun 2 | — |
How to grow sweet cornAll zonesSweet Corn in zone 4aSweet Corn in zone 5aAbout zone 4b
Sources
- How to Grow Sweet Corn in Your Garden · Utah State University Extension
- Growing Sweet Corn in a Home Garden · University of Maryland Extension
- Growing Home Garden Sweet Corn (Circular 905) · University of Georgia Cooperative Extension
- Sweet Corn (HGIC factsheet) · Clemson Cooperative Extension Home & Garden Information Center
- Florida Vegetable Gardening Guide (SP103/VH021) · University of Florida IFAS Extension
- Vegetable Planting Calendar for Maricopa County (AZ1005) · University of Arizona Cooperative Extension
- GN 154: Soil Temperature Conditions for Vegetable Seed Germination (Harrington emergence table) · UC Cooperative Extension, Sacramento County (UC ANR)
- Fall Vegetable Gardening (SPES-801) · Virginia Cooperative Extension