When to plant thyme in Detroit, Michigan
April 21 – May 5
Transplant outdoors · typical Detroit yearClimate basis: NOAA station Detroit City AP, MI (USW00014822), 6 mi (9 km) from downtown Detroit (ZCTA 48226 centroid), elevation 626 ft, on the 1991–2020 climate normals. Transplant thyme outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (April 21). One year in ten still freezes after May 6.
The Detroit year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to May 6
Every method, with its sources
Transplant outdoors
Apr 21 – May 5Oklahoma State Table 1: plant thyme after the last spring frost (seed or cuttings; most gardeners set out plants). Point rule given a 14-day span. Anchored to the median last spring freeze (Apr 21). Oklahoma State University Extension
Start seeds indoors
Not calculatedThe cited guide gives no indoor seed-starting lead time for thyme, so no window is calculated.
Direct-sow outdoors
Not calculatedThe cited extension guides do not time direct sowing for this crop.
Fall planting
Not calculatedNo source-backed fall planting rule exists for this crop in the registry, so no fall window is calculated.
Variety assumption: A hardy perennial once established; harvest lightly the first season.
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)
- Oklahoma State University Extension: Culinary Herbs for Oklahoma Gardens: Culture, Use and Preservation (accessed 2026-07-24)Table 1 planting times relative to last spring frost for common herbs.