When to plant lemon balm in Oklahoma City, Oklahoma

April 4 – April 18

Transplant outdoors · typical Oklahoma City year

Climate basis: NOAA station Oklahoma City Will Rogers AP, OK (USW00013967), 7 mi (12 km) from downtown Oklahoma City (ZCTA 73102 centroid), elevation 1285 ft, on the 1991–2020 climate normals. Transplant lemon balm 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 20.

Last spring freezeApril 41-in-10 after Apr 20

First fall freezeNovember 21-in-10 before Oct 21

Frost-free season≈ 213 daysmedian at 32°F

Hard freeze, 28°Mar 21 – Nov 11kills even hardy greens

USDA zone7b5 to 10°F winter low — not frost timing

The Oklahoma City year

Start seeds indoorsFeb 21 – Mar 7

Transplant outdoorsApr 4 – Apr 18

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to Apr 20

Lemon Balm in Oklahoma City · freeze context from Oklahoma City Will Rogers AP, OK, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Feb 21 – Mar 7

Wisconsin Horticulture sows lemon balm indoors about 4 to 6 weeks before the last spring frost, so the window runs 6 to 4 weeks before that date. Anchored to the median last spring freeze (Apr 4). University of Wisconsin-Madison Division of Extension, Wisconsin Horticulture · Virginia Cooperative Extension, Virginia Tech

Transplant outdoors

Apr 4 – Apr 18

Wisconsin Horticulture ties lemon balm transplanting to seedling height rather than a date, so the frost anchor comes from Virginia Cooperative Extension's herb publication — whose herb table lists lemon balm — which sets all herb plants out after the danger of severe frost has passed. Anchored to the median last spring freeze (Apr 4). Virginia Cooperative Extension, Virginia Tech

Variety assumption: A hardy perennial that self-seeds freely; these windows apply to first-year plantings from seed or nursery plants.

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)

University of Wisconsin-Madison Division of Extension, Wisconsin Horticulture: Lemon Balm, Melissa officinalis (accessed 2026-07-25)
"Lemon balm can be started from seed sown indoors about 4 to 6 weeks before the last spring frost, although seeds may be somewhat slow to germinate."
Virginia Cooperative Extension, Virginia Tech: Herb Culture and Use (Publication 426-420) (accessed 2026-07-25)
"In addition, many culinary herbs, such as tarragon, can only be propagated asexually; seed-grown plants lack the oils that give them flavor."

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