When to plant kohlrabi in Rochester, New York

March 27 – April 10

Transplant outdoors · typical Rochester year

Climate basis: NOAA station Rochester Gtr INTL AP, NY (USW00014768), 5 mi (7 km) from downtown Rochester (ZCTA 14604 centroid), elevation 533 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 8.

Last spring freezeApril 241-in-10 after May 8

First fall freezeOctober 251-in-10 before Oct 8

Frost-free season≈ 181 daysmedian at 32°F

Hard freeze, 28°Apr 14 – Nov 6kills even hardy greens

USDA zone6b-5 to 0°F winter low — not frost timing

The Rochester year

Start seeds indoorsFeb 13 – Feb 27

Transplant outdoorsMar 27 – Apr 10

Fall plantingAug 30 – Sep 27

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 8

Kohlrabi in Rochester · freeze context from Rochester Gtr INTL AP, NY, 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

Aug 30 – Sep 27

Purdue Table 2: plant fall kohlrabi at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Oct 25). 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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