When to plant celeriac in Manchester, New Hampshire

April 30 – May 14

Transplant outdoors · typical Manchester year

Climate basis: NOAA station Massabesic Lake, NH (USC00275211), 4 mi (6 km) from downtown Manchester (ZCTA 03101 centroid), elevation 253 ft, on the 1991–2020 climate normals. Transplant celeriac outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (April 30). One year in ten still freezes after May 14.

Last spring freezeApril 301-in-10 after May 14

First fall freezeOctober 111-in-10 before Sep 30

Frost-free season≈ 164 daysmedian at 32°F

Hard freeze, 28°Apr 17 – Oct 24kills even hardy greens

USDA zone6a-10 to -5°F winter low — not frost timing

The Manchester year

Start seeds indoorsFeb 19 – Mar 5

Transplant outdoorsApr 30 – May 14

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 14

Celeriac in Manchester · freeze context from Massabesic Lake, NH, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Feb 19 – Mar 5

The UC Master Gardener Program of Sonoma County (University of California Cooperative Extension) says to "Sow seed indoors as early as 10 weeks before the average last frost date in spring," so the sowing span opens ten weeks before the last frost and runs two weeks; no competing extension figure was found, so this stands without reconciliation. Anchored to the median last spring freeze (Apr 30). University of California Cooperative Extension, UC Master Gardener Program of Sonoma County

Transplant outdoors

Apr 30 – May 14

The same UC Master Gardener page states plants "can go into the garden 10-12 in. apart on the average date of last frost," a point rule that opens a 14-day transplanting span at the last frost date; the page's alternative air- and soil-temperature condition is not frost-anchored and was therefore not encoded. Anchored to the median last spring freeze (Apr 30). University of California Cooperative Extension, UC Master Gardener Program of Sonoma County

Variety assumption: Assumes a standard 100-to-120-day celeriac variety grown from transplants; germination is slow, so the long indoor lead time is part of the published rule rather than an added buffer.

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 (1)

University of California Cooperative Extension, UC Master Gardener Program of Sonoma County: Celeriac (accessed 2026-07-25)
"Sow seed indoors as early as 10 weeks before the average last frost date in spring."

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