There are plenty of "old wives' tales" that old-time gardeners like to use to predict the last frost date on the calendar before planting their gardens. In this episode, Tim expresses some skepticism toward these silly superstitions and points to the metric of historical averages for one’s area as a more reliable method to use. 

Resources:
https://www.almanac.com/gardening/frostdates
https://davesgarden.com/guides/freeze-frost-dates/
https://www.ncdc.noaa.gov/news/when-expect-your-last-spring-freeze