When to plant sweet marjoram in Portland, Oregon
February 25 – March 11
Transplant outdoors · typical Portland yearClimate basis: NOAA station Portland Kgw-tv, OR (USC00356749), 1 mi (1 km) from downtown Portland (ZCTA 97204 centroid), elevation 159 ft, on the 1991–2020 climate normals. Transplant sweet marjoram outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (February 25). One year in ten still freezes after March 21.
The Portland year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to Mar 21
Every method, with its sources
Start seeds indoors
Dec 31 – Jan 14NC State's Extension Gardener Plant Toolbox starts marjoram seed indoors about 6 to 8 weeks before the last spring frost date, and Clemson HGIC gives the identical 6-to-8-week lead, so the two sources agree. Anchored to the median last spring freeze (Feb 25). NC State Extension, North Carolina Extension Gardener Plant Toolbox · Clemson University Cooperative Extension, Home & Garden Information Center
Transplant outdoors
Feb 25 – Mar 11Clemson HGIC sets marjoram transplants out after the last killing frost and UMD Extension names marjoram among herbs planted outside after the danger of frost has passed; both agree, so the window opens at the last spring freeze. Anchored to the median last spring freeze (Feb 25). Clemson University Cooperative Extension, Home & Garden Information Center
Direct-sow outdoors
Feb 11 – Feb 25NC State's Extension Gardener Plant Toolbox gives a point rule — sow seed directly outdoors about two weeks before the last spring frost date — which opens a two-week sowing span ending at the last freeze; note the transplant window for this tender herb is later. Anchored to the median last spring freeze (Feb 25). NC State Extension, North Carolina Extension Gardener Plant Toolbox
Variety assumption: Grown as an annual across most of the US; NC State's plant toolbox treats it as a tender perennial that is replaced each year in cold climates.
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 (2)
- NC State Extension, North Carolina Extension Gardener Plant Toolbox: Origanum majorana (Knotted Marjoram, Marjoram, Pot Marjoram, Sweet Marjoram) (accessed 2026-07-25)"To plant from seed, start seeds indoors about 6 to 8 weeks prior to the last spring frost date."
- Clemson University Cooperative Extension, Home & Garden Information Center: Herbs (accessed 2026-07-25)"Start seed indoors 6 to 8 weeks before planting or set transplants out after the last killing frost."