When to plant onions in zone 6b
In zone 6b, where the last spring frost typically comes around April 23, start onions indoors January 1 to February 12 and plant out March 26 to April 9.
The zone 6b schedule for onions
- Start seeds indoors
- January 1 to February 12
- Plant out
- March 26 to April 9
- Sow outdoors
- March 12 to 26
From the median frost dates of the NOAA stations assigned to the 4,514 ZIP codes in zone 6b, and the timing recommended by Cooperative Extension guides for onions.
Dates before the last frost assume the soil has thawed and is dry enough to work: a squeezed handful crumbles instead of sticking. After a late or wet spring, wait for that even if the date has passed.
Frost risk in zone 6b
Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 6b, the typical last frost ranges from about April 10 in the earliest tenth of ZIP codes to May 6 in the latest tenth, and the first fall frost from October 9 to October 29. For a typical place in the zone:
- April 8Risky: a later frost happens in 9 years out of 10
- April 23Typical: frost after this date in half of years
- May 9Safe: a later frost only 1 year in 10
Your dates for onions
Set your ZIP code at the top of the page and we will work out when to plant onions where you live, from the frost records of the nearest NOAA weather station. Your ZIP code is remembered on this device only.
Onions in zone 6b cities
| City | Typical last frost | Start indoors | Plant out |
|---|---|---|---|
| Columbus, OH | Apr 18 | Dec 27 to Feb 7 | Mar 21 to Apr 4 |
| Boston, MA | Apr 4 | Dec 13 to Jan 24 | Mar 7 to 21 |
| Detroit, MI | Apr 21 | Dec 30 to Feb 10 | Mar 24 to Apr 7 |
| Kansas City, MO | Apr 4 | Dec 13 to Jan 24 | Mar 7 to 21 |
| Cleveland, OH | Apr 8 | Dec 17 to Jan 28 | Mar 11 to 25 |
| Cincinnati, OH | Apr 16 | Dec 25 to Feb 5 | Mar 19 to Apr 2 |
| Pittsburgh, PA | Apr 24 | Jan 2 to Feb 13 | Mar 27 to Apr 10 |
| Buffalo, NY | Apr 24 | Jan 2 to Feb 13 | Mar 27 to Apr 10 |
| Toledo, OH | Apr 20 | Dec 29 to Feb 9 | Mar 23 to Apr 6 |
| Boise City, ID | Apr 24 | Jan 2 to Feb 13 | Mar 27 to Apr 10 |
| Spokane, WA | Apr 26 | Jan 4 to Feb 15 | Mar 29 to Apr 12 |
| Rochester, NY | Apr 24 | Jan 2 to Feb 13 | Mar 27 to Apr 10 |
How to grow onionsAll zonesOnions in zone 6aOnions in zone 7aAbout zone 6b
Sources
- How to Grow Onions in Your Garden · Utah State University Extension
- Growing Onions in a Home Garden · University of Maryland Extension
- How to Start Onions and Leeks from Seeds · University of Maryland Extension (Maryland Grows)
- Growing Onions - Sets, Plants or Seeds? · Nebraska Extension in Lancaster County
- How to Grow Onions · University of Vermont Extension
- Onions (food fact sheet) · Montana State University Extension
- Planting the Garden · University of Vermont Extension
- Rhode Island Planting Calendar for Fruits and Vegetables · University of Rhode Island Cooperative Extension
- Soil temperature conditions for vegetable seed germination · Oregon State University Extension Service
- Onion, Leek, Shallot, & Garlic (HGIC) · Clemson Cooperative Extension Home & Garden Information Center
- Allium cepa (Plant Toolbox) · NC State Extension
- SP 103/VH021: Florida Vegetable Gardening Guide · University of Florida IFAS Extension
- Onions and Shallots · University of Florida IFAS Gardening Solutions
- Onions (Easy Gardening) · Texas A&M AgriLife Extension
- Vegetable Planting Calendar for Maricopa County (AZ1005) · University of Arizona Cooperative Extension