Last frost date in Castle Pines, Colorado

May 9

Average last frost in spring. In an early year (1 in 10) it's over by April 30; in a late year (1 in 10) it comes after May 24.

October 2

Average first frost in fall. 1 year in 10 it comes by September 17.

Source: NOAA U.S. Climate Normals 1991–2020, station Castle Rock (USC00051401), 4 miles from Castle Pines, elevation 6,185 ft. NOAA National Centers for Environmental Information. These are long-term averages, not a forecast.

What to plant now

Frost dates for Castle Pines, Colorado
Early yearAverageLate year
Last frost in springApr 30May 9May 24
First frost in fallSept 17Oct 2Oct 16

An early or late year is one in 10: 1 year in 10 the frost comes before the early date, and 1 year in 10 after the late date.

Frost-free days in an average year: 143

Planting calendar for Castle Pines

Fall planting

USDA dates for places whose average first freeze is about September 30 (Castle Pines: October 2).

USDA lists chervil and chives, garlic, horseradish, leeks, onion plants, onion seed, onion sets, shallots as generally spring-planted here.

Spring planting

USDA dates for places whose average last freeze is about May 10 (Castle Pines: May 9).

Planting dates: USDA Home and Garden Bulletin No. 9 (1967), “Suburban and Farm Vegetable Gardens,” tables 4 and 5 (earliest safe spring and latest safe fall dates), applied to this place's NOAA frost dates. “Plants” means setting out transplants, not sowing seed. How we match the table.

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