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When to plant sweet potatoes in zone 4b

In zone 4b, where the last spring frost typically comes around May 8, plant out June 12 to 19.

The zone 4b schedule for sweet potatoes

Plant out
June 12 to 19
Soil warm enough (65°F), about
June 12
First harvest, roughly
September 10 to October 17

From the median frost dates of the NOAA stations assigned to the 1,164 ZIP codes in zone 4b, and the timing recommended by Cooperative Extension guides for sweet potatoes.

Frost risk in zone 4b

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 4b, the typical last frost ranges from about May 1 in the earliest tenth of ZIP codes to May 25 in the latest tenth, and the first fall frost from September 22 to October 8. For a typical place in the zone:

  • April 26Risky: a later frost happens in 9 years out of 10
  • May 8Typical: frost after this date in half of years
  • May 22Safe: a later frost only 1 year in 10

Sweet Potatoes 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 sweet potatoes

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

Sweet Potatoes in zone 4b cities

CityTypical last frostPlantFall
Rochester, MNApr 30Jun 6 to 13—
Duluth, MNMay 6Jul 6 to 13—
Lakeville, MNMay 2Jun 8 to 15—
St. Cloud, MNMay 7Jun 12 to 19—
Eau Claire, WIMay 8Jun 8 to 15—
Great Falls, MTMay 19Jul 6 to 13—

How to grow sweet potatoesAll zonesSweet Potatoes in zone 4aSweet Potatoes in zone 5aAbout zone 4b

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