When to plant rosemary in Boston, Massachusetts
April 4 – April 18
Transplant outdoors · typical Boston yearClimate basis: NOAA station Boston Logan INTL AP, MA (USW00014739), 3 mi (5 km) from downtown Boston (ZCTA 02108 centroid), elevation 12 ft, on the 1991–2020 climate normals. Transplant rosemary outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (April 4). One year in ten still freezes after April 17.
The Boston year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to Apr 17
Every method, with its sources
Transplant outdoors
Apr 4 – Apr 18Oklahoma State Table 1: plant rosemary after the last spring frost (propagated by seed or cuttings; most gardeners set out purchased plants). Point rule given a 14-day span. Anchored to the median last spring freeze (Apr 4). Oklahoma State University Extension
Start seeds indoors
Not calculatedSeed-started rosemary is slow and erratic; the cited guide gives no indoor lead time, 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 slow-growing perennial; harvest lightly the first season. Not reliably winter-hardy in cold zones.
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.