When to plant snapdragon 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 snapdragon 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 indoorsMar 8 – Mar 22

Transplant outdoorsApr 5 – Apr 19

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

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

Every method, with its sources

Start seeds indoors

Mar 8 – Mar 22

Colorado State's seed-starting table lists snapdragon at 8 weeks before the average frost-free date in the 'Indoors' column, the longest lead time of any source found, so indoor sowing opens 8 weeks before the median last freeze and runs a two-week span. Anchored to the median last spring freeze (May 3). Colorado State University Extension

Transplant outdoors

Apr 5 – Apr 19

Illinois Extension names snapdragon in its hardy-annual list and states those can usually be planted about four weeks before the frost-free date, and NC State agrees hardy annuals go out in spring before the last frost date, so transplanting opens 4 weeks before the median last freeze. Anchored to the median last spring freeze (May 3). NC State Extension

Variety assumption: Assumes ordinary bedding and cut-flower strains of Antirrhinum majus grown as an annual; it is a hardy annual that flowers best in cool weather and Colorado State's 8-week indoor lead time reflects its slow start from very fine 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 (2)

Colorado State University Extension: Growing Annual Plants from Seed (accessed 2026-07-25)
"Table 1: Starting times for seeds grown indoors and in cold frames, shown as number of weeks to start seed before average frost-free date."
NC State Extension: Extension Gardener Handbook, Ch. 10: Herbaceous Ornamentals (accessed 2026-07-25)
"Hardy annuals are the most cold-tolerant. They tolerate light frost and some freezing weather without being killed. In most cases, hardy annuals are planted in the fall or in the spring before the last frost date."

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