When to plant kohlrabi in Fargo, North Dakota

April 12 – April 26

Transplant outdoors · typical Fargo year

Climate basis: NOAA station Fargo Hector INTL AP, ND (USW00014914), 1 mi (2 km) from downtown Fargo (ZCTA 58102 centroid), elevation 900 ft, on the 1991–2020 climate normals. Transplant kohlrabi outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (May 10). One year in ten still freezes after May 23.

Last spring freezeMay 101-in-10 after May 23

First fall freezeSeptember 301-in-10 before Sep 18

Frost-free season≈ 143 daysmedian at 32°F

Hard freeze, 28°Apr 30 – Oct 10kills even hardy greens

USDA zone4a-30 to -25°F winter low — not frost timing

The Fargo year

Start seeds indoorsMar 1 – Mar 15

Transplant outdoorsApr 12 – Apr 26

Fall plantingAug 5 – Sep 2

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 23

Kohlrabi in Fargo · freeze context from Fargo Hector INTL AP, ND, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Mar 1 – Mar 15

Sow 4–6 weeks before the set-out window opens (UNH: time from seed to transplant 4–6 weeks). Anchored to the median last spring freeze (May 10). University of New Hampshire Extension

Transplant outdoors

Apr 12 – Apr 26

UNH: safe to set out 4 weeks before the last frost; Purdue's hardy class allows 4–6 weeks before. The later UNH start is used. Anchored to the median last spring freeze (May 10). University of New Hampshire Extension · Purdue University Extension

Fall planting

Aug 5 – Sep 2

Purdue Table 2: plant fall kohlrabi at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Sep 30). Purdue University Extension

These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.

This week, not a typical year:

Crop rule sources (2)

University of New Hampshire Extension: Growing Vegetables: When to Plant Your Vegetable Garden [fact sheet] (accessed 2026-07-24)
Per-crop 'time from seed to transplant' and 'safe to set out in garden' relative to last frost.
Purdue University Extension: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-24)
Hardiness classes: hardy = plant 4-6 wk before last spring frost; semi-hardy = 2-4 wk before; tender = after average last frost; very tender = at least 2 wk after. Table 2: fall planting at least 4-8 wk before first fall frost.

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