When to plant parsley in Billings, Montana

April 19 – May 3

Transplant outdoors · typical Billings year

Climate basis: NOAA station Billings Wtp, MT (USC00240802), 13 mi (21 km) from downtown Billings (ZCTA 59101 centroid), elevation 3097 ft, on the 1991–2020 climate normals. Transplant parsley outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (May 10). One year in ten still freezes after May 24.

Last spring freezeMay 101-in-10 after May 24

First fall freezeOctober 11-in-10 before Sep 19

Frost-free season≈ 142 daysmedian at 32°F

Hard freeze, 28°Apr 27 – Oct 12kills even hardy greens

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

The Billings year

Start seeds indoorsFeb 8 – Feb 22

Transplant outdoorsApr 19 – May 3

Direct-sow outdoorsApr 12 – Apr 26

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 24

Parsley in Billings · freeze context from Billings Wtp, MT, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Feb 8 – Feb 22

Wisconsin: start seeds indoors 8–10 weeks before the last frost (UNH: 9–10 weeks from seed to transplant). Parsley germinates slowly. Anchored to the median last spring freeze (May 10). University of Wisconsin–Madison Division of Extension (Wisconsin Horticulture) · University of New Hampshire Extension

Transplant outdoors

Apr 19 – May 3

UNH: set out 2–3 weeks before the last frost; Oklahoma State plants 3–4 weeks before. The later UNH range is used. Anchored to the median last spring freeze (May 10). University of New Hampshire Extension · Oklahoma State University Extension

Direct-sow outdoors

Apr 12 – Apr 26

Oklahoma State Table 1: plant parsley three to four weeks before the last spring frost. Anchored to the median last spring freeze (May 10). Oklahoma State University Extension

Variety assumption: Leaf harvest begins about 70–90 days from seed.

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 (3)

University of Wisconsin–Madison Division of Extension (Wisconsin Horticulture): Parsley, Petroselinum crispum (accessed 2026-07-24)
"Start seeds indoors 8-10 weeks before last frost."
University of New Hampshire Extension: Growing Vegetables: When to Plant Your Vegetable Garden [fact sheet] (accessed 2026-07-24)
Per-crop 'time from seed to transplant' and 'safe to set out in garden' relative to last frost.
Oklahoma State University Extension: Culinary Herbs for Oklahoma Gardens: Culture, Use and Preservation (accessed 2026-07-24)
Table 1 planting times relative to last spring frost for common herbs.

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