When to plant kohlrabi in Washington, District of Columbia

February 24 – March 10

Transplant outdoors · typical Washington year

Climate basis: NOAA station Washington Reagan AP, VA (USW00013743), 3 mi (5 km) from downtown Washington (ZCTA 20004 centroid), elevation 10 ft, on the 1991–2020 climate normals. Transplant kohlrabi outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (March 24). One year in ten still freezes after April 6.

Last spring freezeMarch 241-in-10 after Apr 6

First fall freezeNovember 181-in-10 before Nov 5

Frost-free season≈ 241 daysmedian at 32°F

Hard freeze, 28°Mar 12 – Dec 3kills even hardy greens

The Washington year

Start seeds indoorsJan 13 – Jan 27

Transplant outdoorsFeb 24 – Mar 10

Fall plantingSep 23 – Oct 21

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to Apr 6

Kohlrabi in Washington · freeze context from Washington Reagan AP, VA, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Jan 13 – Jan 27

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 (Mar 24). University of New Hampshire Extension

Transplant outdoors

Feb 24 – Mar 10

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 (Mar 24). University of New Hampshire Extension · Purdue University Extension

Fall planting

Sep 23 – Oct 21

Purdue Table 2: plant fall kohlrabi at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Nov 18). 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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