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When to plant zinnias in zone 6b

In zone 6b, where the last spring frost typically comes around April 23, start zinnias indoors May 18 to 25 and plant out June 15 to 29.

The zone 6b schedule for zinnias

Start seeds indoors
May 18 to 25
Plant out
June 15 to 29
Sow outdoors
June 15 to 29
Soil warm enough (70°F), about
June 15

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 zinnias.

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

Zinnias 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 zinnias

Set your ZIP code at the top of the page and we will work out when to plant zinnias where you live, from the frost records of the nearest NOAA weather station. Your ZIP code is remembered on this device only.

Enter your ZIP code

Zinnias in zone 6b cities

CityTypical last frostStart indoorsPlant out
Columbus, OHApr 18May 11 to 18Jun 8 to 22
Boston, MAApr 4May 25 to Jun 1Jun 22 to Jul 6
Detroit, MIApr 21May 19 to 26Jun 16 to 30
Kansas City, MOApr 4Apr 28 to May 5May 26 to Jun 9
Cleveland, OHApr 8May 18 to 25Jun 15 to 29
Cincinnati, OHApr 16May 10 to 17Jun 7 to 21
Pittsburgh, PAApr 24May 18 to 25Jun 15 to 29
Buffalo, NYApr 24Jun 1 to 8Jun 29 to Jul 13
Toledo, OHApr 20May 15 to 22Jun 12 to 26
Boise City, IDApr 24May 27 to Jun 3Jun 24 to Jul 8
Spokane, WAApr 26Jun 11 to 18Jul 9 to 23
Rochester, NYApr 24May 28 to Jun 4Jun 25 to Jul 9

How to grow zinniasAll zonesZinnias in zone 6aZinnias in zone 7aAbout zone 6b

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