A thick layer of mulch around perennials can help them survive winter by insulating the roots against cold temperatures

https://pr.ashlandtownnews.com/article/Landscape-Supply-House-Grand-Opening-Lubbocks-New-Destination-for-Landscape-Professionals?storyId=67cafe02bb465f0008aa0d59

A thick layer of mulch around perennials can help them survive winter by insulating the roots against cold temperatures and harsh weather conditions.