When to plant brussels sprouts in Colorado Springs, Colorado

April 5 – April 19

Transplant outdoors · typical Colorado Springs year

Climate basis: NOAA station Colorado Springs Muni AP, CO (USW00093037), 7 mi (11 km) from downtown Colorado Springs (ZCTA 80903 centroid), elevation 6181 ft, on the 1991–2020 climate normals. Transplant brussels sprouts outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (May 3). One year in ten still freezes after May 15.

Last spring freezeMay 31-in-10 after May 15

First fall freezeOctober 81-in-10 before Sep 26

Frost-free season≈ 158 daysmedian at 32°F

Hard freeze, 28°Apr 24 – Oct 16kills even hardy greens

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

The Colorado Springs year

Start seeds indoorsFeb 22 – Mar 8

Transplant outdoorsApr 5 – Apr 19

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 15

Brussels sprouts in Colorado Springs · freeze context from Colorado Springs Muni AP, CO, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Feb 22 – Mar 8

Sow 4–6 weeks before the set-out window opens (UNH 4–6 weeks; Missouri G6570 6–8 weeks). Anchored to the median last spring freeze (May 3). University of New Hampshire Extension · University of Missouri Extension

Transplant outdoors

Apr 5 – Apr 19

UNH: set out 2–4 weeks before the last frost; Purdue's hardy class allows 4–6 weeks before. The later UNH range is used. Anchored to the median last spring freeze (May 3). University of New Hampshire Extension · Purdue University Extension

Variety assumption: A long-season crop (about 90–110 days from transplant); sprouts sweeten after light fall frosts.

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 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.
University of Missouri Extension: Starting Plants Indoors from Seeds (G6570) (accessed 2026-07-24)
Weeks needed to grow vegetable transplants indoors (Table 2).
Purdue University Extension: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-24)
Hardiness classes: hardy = plant 4-6 wk before last spring frost; semi-hardy = 2-4 wk before; tender = after average last frost; very tender = at least 2 wk after. Table 2: fall planting at least 4-8 wk before first fall frost.

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