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When to plant basil in zone 5b

In zone 5b, where the last spring frost typically comes around May 1, start basil indoors April 4 to 18 and plant out May 23 to 30.

The zone 5b schedule for basil

Start seeds indoors
April 4 to 18
Plant out
May 23 to 30
Sow outdoors
May 23 to 30
Soil warm enough (60°F), about
May 23
First harvest, roughly
June 22 to 29

From the median frost dates of the NOAA stations assigned to the 2,546 ZIP codes in zone 5b, and the timing recommended by Cooperative Extension guides for basil.

Frost risk in zone 5b

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 5b, the typical last frost ranges from about April 21 in the earliest tenth of ZIP codes to May 18 in the latest tenth, and the first fall frost from September 30 to October 19. For a typical place in the zone:

  • April 18Risky: a later frost happens in 9 years out of 10
  • May 1Typical: frost after this date in half of years
  • May 16Safe: a later frost only 1 year in 10

Basil 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 basil

Set your ZIP code at the top of the page and we will work out when to plant basil 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

Basil in zone 5b cities

CityTypical last frostStart indoorsPlant out
Milwaukee, WIApr 19Apr 6 to 20May 25 to Jun 1
Madison, WIMay 1Apr 3 to 17May 22 to 29
Des Moines, IAApr 18Mar 22 to Apr 5May 10 to 17
Aurora, ILApr 19Mar 27 to Apr 10May 15 to 22
Fort Collins, COMay 2Apr 4 to 18May 23 to 30
Naperville, ILApr 19Mar 27 to Apr 10May 15 to 22
Rockford, ILApr 24Mar 27 to Apr 10May 15 to 22
Elgin, ILApr 26Mar 30 to Apr 13May 18 to 25
Greeley, COMay 2Mar 30 to Apr 13May 18 to 25
Green Bay, WIApr 30Apr 7 to 21May 26 to Jun 2
Davenport, IAApr 19Mar 24 to Apr 7May 12 to 19
Longmont, COMay 6Apr 6 to 20May 25 to Jun 1

How to grow basilAll zonesBasil in zone 5aBasil in zone 6aAbout zone 5b

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