When to plant celeriac in Grand Rapids, Michigan
May 6 – May 20
Transplant outdoors · typical Grand Rapids yearClimate basis: NOAA station E Grand Rapids, MI (USC00202375), 3 mi (5 km) from downtown Grand Rapids (ZCTA 49503 centroid), elevation 746 ft, on the 1991–2020 climate normals. Transplant celeriac outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (May 6). One year in ten still freezes after May 23.
The Grand Rapids year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to May 23
Every method, with its sources
Start seeds indoors
Feb 25 – Mar 11The 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 (May 6). University of California Cooperative Extension, UC Master Gardener Program of Sonoma County
Transplant outdoors
May 6 – May 20The 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 (May 6). 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.
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."