When to plant kohlrabi in Pittsburgh, Pennsylvania

March 27 – April 10

Transplant outdoors · typical Pittsburgh year

Climate basis: NOAA station Emsworth L/d Ohio Rvr, PA (USC00362574), 6 mi (10 km) from downtown Pittsburgh (ZCTA 15222 centroid), elevation 717 ft, on the 1991–2020 climate normals. Transplant kohlrabi outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (April 24). One year in ten still freezes after May 11.

Last spring freezeApril 241-in-10 after May 11

First fall freezeOctober 271-in-10 before Oct 13

Frost-free season≈ 186 daysmedian at 32°F

Hard freeze, 28°Apr 12 – Nov 5kills even hardy greens

USDA zone7a0 to 5°F winter low — not frost timing

The Pittsburgh year

Start seeds indoorsFeb 13 – Feb 27

Transplant outdoorsMar 27 – Apr 10

Fall plantingSep 1 – Sep 29

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 11

Kohlrabi in Pittsburgh · freeze context from Emsworth L/d Ohio Rvr, PA, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Feb 13 – Feb 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 (Apr 24). University of New Hampshire Extension

Transplant outdoors

Mar 27 – Apr 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 (Apr 24). University of New Hampshire Extension · Purdue University Extension

Fall planting

Sep 1 – Sep 29

Purdue Table 2: plant fall kohlrabi at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Oct 27). 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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