FAQ

I wasn't sure the extent of your question, whether you were referring to vegetables, annuals, perennials, or woody plants since there are favorable times for each considering on what you are planting.  I'm going to be quite general in my response.  Usually frost dates are the limiting factors for most plants, but there are cool season vegetables such as spinach, beets and carrots that can be planted in early spring that can withstand some cold temperatures whereas vegetables like tomatoes, peppers, and corn need warm soil temperatures to survive.

Not knowing where you live, I will send you the link to the Utah Climate Center which has a listing of weather stations throughout Utah and you can find one near you to find out the average last spring frost and first fall frost dates.

http://climate.usurf.usu.edu/reports/freezeDates.php

The way to read the data is to first find your location (see example below).  I’ve pasted the information for one of the five Salt Lake City stations and you read the column as follows:

For this location, average last spring freeze is April 11 and average first fall freeze is October 31 with average of 205 freeze free days.  

There is more detailed information on specific plants (waterwise, vegetables, trees) from USU Extension website.