When to plant lemon balm in Pittsburgh, Pennsylvania

April 24 – May 8

Transplant outdoors · typical Pittsburgh year

Climate basis: NOAA station Emsworth L/d Ohio Rvr, PA (USC00362574), 6 mi (10 km) from downtown Pittsburgh (ZCTA 15222 centroid), elevation 717 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 24). One year in ten still freezes after May 11.

Last spring freezeApril 241-in-10 after May 11

First fall freezeOctober 271-in-10 before Oct 13

Frost-free season≈ 186 daysmedian at 32°F

Hard freeze, 28°Apr 12 – Nov 5kills even hardy greens

USDA zone7a0 to 5°F winter low — not frost timing

The Pittsburgh year

Start seeds indoorsMar 13 – Mar 27

Transplant outdoorsApr 24 – May 8

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 11

Lemon Balm in Pittsburgh · freeze context from Emsworth L/d Ohio Rvr, PA, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Mar 13 – Mar 27

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 24). University of Wisconsin-Madison Division of Extension, Wisconsin Horticulture · Virginia Cooperative Extension, Virginia Tech

Transplant outdoors

Apr 24 – May 8

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 24). 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."

Keep exploring

This crop, other cities

Related crops in Pittsburgh

Local overview