When to plant parsley in Denver, Colorado

April 9 – April 23

Transplant outdoors · typical Denver year

Climate basis: NOAA station Denver Water Dept, CO (USC00052223), 2 mi (3 km) from downtown Denver (ZCTA 80202 centroid), elevation 5228 ft, on the 1991–2020 climate normals. Transplant parsley outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (April 30). One year in ten still freezes after May 13.

Last spring freezeApril 301-in-10 after May 13

First fall freezeOctober 121-in-10 before Sep 28

Frost-free season≈ 165 daysmedian at 32°F

Hard freeze, 28°Apr 18 – Oct 21kills even hardy greens

USDA zone6a-10 to -5°F winter low — not frost timing

The Denver year

Start seeds indoorsJan 29 – Feb 12

Transplant outdoorsApr 9 – Apr 23

Direct-sow outdoorsApr 2 – Apr 16

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 13

Parsley in Denver · freeze context from Denver Water Dept, CO, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Jan 29 – Feb 12

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 (Apr 30). University of Wisconsin–Madison Division of Extension (Wisconsin Horticulture) · University of New Hampshire Extension

Transplant outdoors

Apr 9 – Apr 23

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 (Apr 30). University of New Hampshire Extension · Oklahoma State University Extension

Direct-sow outdoors

Apr 2 – Apr 16

Oklahoma State Table 1: plant parsley three to four weeks before the last spring frost. Anchored to the median last spring freeze (Apr 30). 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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