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When to plant zinnias in zone 6a

In zone 6a, where the last spring frost typically comes around April 29, start zinnias indoors May 20 to 27 and plant out June 17 to July 1.

The zone 6a schedule for zinnias

Start seeds indoors
May 20 to 27
Plant out
June 17 to July 1
Sow outdoors
June 17 to July 1
Soil warm enough (70°F), about
June 17

From the median frost dates of the NOAA stations assigned to the 4,514 ZIP codes in zone 6a, and the timing recommended by Cooperative Extension guides for zinnias.

Frost risk in zone 6a

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 6a, the typical last frost ranges from about April 16 in the earliest tenth of ZIP codes to May 11 in the latest tenth, and the first fall frost from October 4 to October 24. For a typical place in the zone:

  • April 16Risky: a later frost happens in 9 years out of 10
  • April 29Typical: frost after this date in half of years
  • May 14Safe: 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 6a cities

CityTypical last frostStart indoorsPlant out
Chicago, ILApr 11May 13 to 20Jun 10 to 24
Indianapolis city, INApr 15May 9 to 16Jun 6 to 20
Denver, COMay 4May 23 to 30Jun 20 to Jul 4
Colorado Springs, COMay 3May 30 to Jun 6Jun 27 to Jul 11
Omaha, NEApr 18May 5 to 12Jun 2 to 16
Aurora, COMay 4May 23 to 30Jun 20 to Jul 4
Lincoln, NEApr 24May 6 to 13Jun 3 to 17
Fort Wayne, INApr 24May 16 to 23Jun 13 to 27
Grand Rapids, MIApr 29May 23 to 30Jun 20 to Jul 4
Lakewood, COMay 5May 31 to Jun 7Jun 28 to Jul 12
Springfield, MAMay 3May 28 to Jun 4Jun 25 to Jul 9
Joliet, ILApr 19May 18 to 25Jun 15 to 29

How to grow zinniasAll zonesZinnias in zone 5bZinnias in zone 6bAbout zone 6a

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