When to plant lemon balm in Sioux Falls, South Dakota

May 1 – May 15

Transplant outdoors · typical Sioux Falls year

Climate basis: NOAA station Sioux Falls, SD (USW00014944), 2 mi (3 km) from downtown Sioux Falls (ZCTA 57104 centroid), elevation 1430 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 (May 1). One year in ten still freezes after May 14.

Last spring freezeMay 11-in-10 after May 14

First fall freezeOctober 61-in-10 before Sep 23

Frost-free season≈ 157 daysmedian at 32°F

Hard freeze, 28°Apr 22 – Oct 17kills even hardy greens

USDA zone5a-20 to -15°F winter low — not frost timing

The Sioux Falls year

Start seeds indoorsMar 20 – Apr 3

Transplant outdoorsMay 1 – May 15

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 14

Lemon Balm in Sioux Falls · freeze context from Sioux Falls, SD, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Mar 20 – Apr 3

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 (May 1). University of Wisconsin-Madison Division of Extension, Wisconsin Horticulture · Virginia Cooperative Extension, Virginia Tech

Transplant outdoors

May 1 – May 15

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 (May 1). 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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