When to plant kohlrabi in Burlington, Vermont

April 1 – April 15

Transplant outdoors · typical Burlington year

Climate basis: NOAA station Burlington INTL AP, VT (USW00014742), 3 mi (5 km) from downtown Burlington (ZCTA 05401 centroid), elevation 330 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 29). One year in ten still freezes after May 11.

Last spring freezeApril 291-in-10 after May 11

First fall freezeOctober 151-in-10 before Oct 2

Frost-free season≈ 169 daysmedian at 32°F

Hard freeze, 28°Apr 18 – Oct 28kills even hardy greens

USDA zone5b-15 to -10°F winter low — not frost timing

The Burlington year

Start seeds indoorsFeb 18 – Mar 4

Transplant outdoorsApr 1 – Apr 15

Fall plantingAug 20 – Sep 17

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

Kohlrabi in Burlington · freeze context from Burlington INTL AP, VT, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Feb 18 – Mar 4

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 29). University of New Hampshire Extension

Transplant outdoors

Apr 1 – Apr 15

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 29). University of New Hampshire Extension · Purdue University Extension

Fall planting

Aug 20 – Sep 17

Purdue Table 2: plant fall kohlrabi at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Oct 15). 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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