USDA hardiness zone 6b
In zone 6b, the average annual extreme minimum temperature is -5 to 0°F (-20.6 to -17.8°C), based on 1991–2020 data from the 2023 USDA Plant Hardiness Zone Map.
What zone 6b means for your garden
A plant labeled "hardy to zone 6b" should survive a typical winter low of -5°F. Most perennials sold at garden centers are rated for this zone or colder; marginal plants rated one zone warmer can survive in sheltered spots. Zone 6a is the colder half of zone 6.
ZIP codes in zone 6b: 5,263 in contiguous U.S., 8 in Alaska. New to zones? Read how to read your hardiness zone.
Frost dates in zone 6b
Across 46 major cities in zone 6b, the 30%-risk last spring frost ranges from Apr 8 to Jun 14 (median Apr 26), and the first fall frost has a median of Oct 21. Frost timing depends on elevation, latitude and distance from water — a zone does not set a frost date, so check your city page for local dates.
Typical planting calendar for zone 6b
Based on the median frost dates above. For your exact dates, use your city page.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 1 – Mar 15 | May 3 – May 17 | — | — |
| Pepper | Feb 15 – Mar 1 | May 10 – May 24 | — | — |
| Lettuce | Mar 15 – Mar 29 | Apr 12 – May 3 | Mar 29 – May 10 | Aug 12 – Sep 9 |
| Green Beans | — | — | May 3 – Jun 7 | Jul 29 – Aug 12 |
| Sweet Corn | — | — | May 3 – May 31 | — |
| Zucchini & Summer Squash | Mar 29 – Apr 5 | May 3 – May 17 | May 3 – May 24 | Jul 29 – Aug 12 |
| Cucumber | Mar 29 – Apr 5 | May 10 – May 17 | May 3 – May 24 | Jul 29 – Aug 12 |
| Carrot | — | — | Apr 5 – May 10 | Jul 29 – Aug 12 |
| Onion | Feb 1 – Feb 15 | Mar 29 – Apr 12 | — | — |
| Potato | — | Mar 29 – Apr 19 | — | — |
| Basil | Mar 15 – Mar 29 | May 10 – May 24 | May 10 – May 31 | — |
| Spinach | — | — | Mar 15 – Apr 12 | Aug 26 – Sep 23 |
| Kale | Mar 1 – Mar 15 | Mar 29 – Apr 19 | Mar 29 – Apr 19 | Aug 12 – Sep 9 |
| Broccoli | Mar 1 – Mar 15 | Apr 12 – May 3 | — | Jul 29 – Aug 12 |
| Peas | — | — | Mar 15 – Apr 5 | Aug 12 – Aug 26 |
| Eggplant | Feb 15 – Mar 1 | May 10 – May 24 | — | — |
| Cabbage | Mar 1 – Mar 15 | Mar 29 – Apr 12 | — | Jul 29 – Aug 12 |
| Radish | — | — | Mar 22 – May 10 | Sep 9 – Oct 7 |
| Strawberry | — | Mar 29 – Apr 19 | — | — |
| Beets | — | — | Apr 5 – May 17 | Aug 12 – Aug 26 |
Cities in zone 6b (46)
Major cities whose center falls in zone 6b:
- Columbus, OH — last frost Apr 27, first frost Oct 20
- Indianapolis, IN — last frost Apr 26, first frost Oct 16
- Boston, MA — last frost Apr 8, first frost Nov 3
- Detroit, MI — last frost May 2, first frost Oct 20
- Kansas City, MO — last frost Apr 10, first frost Oct 29
- Cincinnati, OH — last frost Apr 24, first frost Oct 21
- Pittsburgh, PA — last frost Apr 24, first frost Oct 22
- Buffalo, NY — last frost Apr 30, first frost Oct 19
- Toledo, OH — last frost Apr 27, first frost Oct 22
- Spokane, WA — last frost May 1, first frost Oct 7
- Rochester, NY — last frost Apr 30, first frost Oct 18
- Overland Park, KS — last frost Apr 16, first frost Oct 23
- Akron, OH — last frost Apr 30, first frost Oct 22
- Springfield, MO — last frost Apr 16, first frost Oct 22
- Kansas City, KS — last frost Apr 10, first frost Oct 29
- Olathe, KS — last frost Apr 16, first frost Oct 23
- Warren, MI — last frost Apr 27, first frost Oct 24
- Dayton, OH — last frost Apr 25, first frost Oct 21
- Sterling Heights, MI — last frost May 5, first frost Oct 18
- Columbia, MO — last frost Apr 12, first frost Oct 25
- Topeka, KS — last frost Apr 20, first frost Oct 17
- Hartford, CT — last frost Apr 23, first frost Oct 20
- Independence, MO — last frost Apr 16, first frost Oct 22
- Cambridge, MA — last frost Apr 8, first frost Nov 3
- Lowell, MA — last frost May 3, first frost Oct 5
- Waterbury, CT — last frost May 1, first frost Oct 11
- Provo, UT — last frost Apr 25, first frost Oct 16
- Bend, OR — last frost Jun 14, first frost Sep 12
- Lee's Summit, MO — last frost Apr 13, first frost Oct 23
- Dearborn, MI — last frost May 8, first frost Oct 9
- Brockton, MA — last frost Apr 28, first frost Oct 13
- Quincy, MA — last frost Apr 30, first frost Oct 15
- Lawrence, KS — last frost Apr 17, first frost Oct 22
- O'Fallon, MO — last frost Apr 16, first frost Oct 20
- Livonia, MI — last frost May 8, first frost Oct 10
- Erie, PA — last frost May 2, first frost Oct 30
- Newton, MA — last frost Apr 24, first frost Oct 16
- Santa Fe, NM — last frost May 20, first frost Oct 1
- Lawrence, MA — last frost Apr 19, first frost Oct 22
- Troy, MI — last frost May 2, first frost Oct 16
- Danbury, CT — last frost May 6, first frost Oct 7
- Cranston, RI — last frost Apr 17, first frost Oct 24
- Westland, MI — last frost Apr 28, first frost Oct 22
- Bloomington, IN — last frost Apr 22, first frost Oct 21
- Parma, OH — last frost Apr 27, first frost Oct 30
- Southfield, MI — last frost May 8, first frost Oct 10
← Zone 6a · Zone 7a → · All zones
Zone 6b questions
How cold does it get in zone 6b?
Zone 6b is defined by an average annual extreme minimum temperature of -5 to 0°F (-20.6 to -17.8°C) for 1991–2020 — the average of each year's single coldest night, not the record low. Individual winters can be colder, so plants rated exactly for zone 6b carry some risk in a severe year.
When is the last frost in zone 6b?
It depends far more on the city than on the zone. Among 46 zone 6b cities on this site, the 30%-risk last spring frost runs from Apr 8 in Boston, MA to Jun 14 in Bend, OR — 67 days apart (median Apr 26).
Which states have zone 6b?
The 2023 listings put 5,271 ZIP codes in zone 6b, spread over 33 states and territories. The most are in Ohio (783), Pennsylvania (761), Missouri (521), Kansas (401), West Virginia (364).
Did zone 6b grow on the 2023 map?
No: 5,356 ZIP codes were in zone 6b on the 2012 map and 5,271 are on the 2023 map (-85). Of today's zone 6b ZIP codes that were also listed in 2012, 65% were in a colder zone then, 34% were already 6b, and 1% were in a warmer zone. What changed in 2023.
Which big cities are in zone 6b?
The largest cities on this site in zone 6b are Columbus, OH, Indianapolis, IN, Boston, MA; 46 cities in all are listed below.