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When to plant zinnias in zone 5a

In zone 5a, where the last spring frost typically comes around May 3, start zinnias indoors May 24 to 31 and plant out June 21 to July 5.

The zone 5a schedule for zinnias

Start seeds indoors
May 24 to 31
Plant out
June 21 to July 5
Sow outdoors
June 21 to July 5
Soil warm enough (70°F), about
June 21

From the median frost dates of the NOAA stations assigned to the 2,200 ZIP codes in zone 5a, and the timing recommended by Cooperative Extension guides for zinnias.

Frost risk in zone 5a

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 5a, the typical last frost ranges from about April 27 in the earliest tenth of ZIP codes to May 21 in the latest tenth, and the first fall frost from September 25 to October 13. For a typical place in the zone:

  • April 20Risky: a later frost happens in 9 years out of 10
  • May 3Typical: frost after this date in half of years
  • May 17Safe: 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 5a cities

CityTypical last frostStart indoorsPlant out
Minneapolis, MNApr 23May 24 to 31Jun 21 to Jul 5
St. Paul, MNApr 23May 24 to 31Jun 21 to Jul 5
Anchorage, AKMay 5Apr 7 to 14May 5 to 19
Sioux Falls, SDMay 1May 19 to 26Jun 16 to 30
Cedar Rapids, IAApr 28May 14 to 21Jun 11 to 25
Billings, MTMay 10Jun 11 to 18Jul 9 to 23
Bloomington, MNApr 23May 21 to 28Jun 18 to Jul 2
Sioux City, IAApr 29May 15 to 22Jun 12 to 26
Brooklyn Park, MNApr 30May 24 to 31Jun 21 to Jul 5
Woodbury, MNApr 24May 22 to 29Jun 19 to Jul 3
Plymouth, MNApr 29May 25 to Jun 1Jun 22 to Jul 6
Blaine, MNApr 30May 24 to 31Jun 21 to Jul 5

How to grow zinniasAll zonesZinnias in zone 4bZinnias in zone 5bAbout zone 5a

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