When to plant snapdragon in Salt Lake City, Utah
March 3 – March 17
Transplant outdoors · typical Salt Lake City yearClimate basis: NOAA station Salt Lake Triad Ctr, UT (USC00427606), 1 mi (2 km) from downtown Salt Lake City (ZCTA 84111 centroid), elevation 4280 ft, on the 1991–2020 climate normals. Transplant snapdragon outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (March 31). One year in ten still freezes after April 19.
The Salt Lake City year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to Apr 19
Every method, with its sources
Start seeds indoors
Feb 3 – Feb 17Colorado 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 (Mar 31). Colorado State University Extension
Transplant outdoors
Mar 3 – Mar 17Illinois 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 (Mar 31). 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.
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."