Last spring frosts
The date of the last spring frost is important to home gardeners planning to set out frost-sensitive annuals, vegetables and even tropical container plants.
Sometimes different frost dates are quoted for each area. This risk factor presents a choice for home gardeners. How much of a chance are you willing to take in placing a tender plant outdoors?
For example, in Denver the last spring frost date at a 50 percent confidence level is May 2nd. This computes to a growing season of 157 days. If you want to be 80 percent confident frosts are past, it's May 12th. If you're not a risk taker and want to be 90 percent confident, wait until May 18th to plant. All dates are based on 47 years of data. The latest frost date in Denver was June 2nd in 1951.
For more information, see the following Colorado State University Extension fact sheet(s).
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Updated Tuesday, November 19, 2013