When to plant sweet marjoram in Cheyenne, Wyoming

May 14 – May 28

Transplant outdoors · typical Cheyenne year

Climate basis: NOAA station Cheyenne Wfo, WY (USC00481676), 7 mi (12 km) from downtown Cheyenne (ZCTA 82001 centroid), elevation 6119 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 (May 14). One year in ten still freezes after May 28.

Last spring freezeMay 141-in-10 after May 28

First fall freezeOctober 11-in-10 before Sep 17

Frost-free season≈ 139 daysmedian at 32°F

Hard freeze, 28°May 3 – Oct 10kills even hardy greens

USDA zone5b-15 to -10°F winter low — not frost timing

The Cheyenne year

Start seeds indoorsMar 19 – Apr 2

Transplant outdoorsMay 14 – May 28

Direct-sow outdoorsApr 30 – May 14

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 28

Sweet Marjoram in Cheyenne · freeze context from Cheyenne Wfo, WY, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Mar 19 – Apr 2

NC 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 (May 14). NC State Extension, North Carolina Extension Gardener Plant Toolbox · Clemson University Cooperative Extension, Home & Garden Information Center

Transplant outdoors

May 14 – May 28

Clemson 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 (May 14). Clemson University Cooperative Extension, Home & Garden Information Center

Direct-sow outdoors

Apr 30 – May 14

NC 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 (May 14). 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.

This week, not a typical year:

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."

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