Whether kalanchoe is invasive or not depends on where you live and what type of kalanchoe it is. The University of Florida writes, “Many species of Kalanchoe have been distributed globally via horticulture, as popular container and landscape plants, and a number of them have escaped cultivation and becoming invasive in many areas. There are ~7 species of Kalanchoe reported outside of cultivation in Florida, with 2 being documented as becoming problematic and both listed as FISC Category II: Kalanchoe pinnata (Cathedral bells) and Kalanchoe x houghtonii (Mother of Millions).” The site continues, “High reproductive rates and an ability to thrive in dry arid environments have allowed them to invade coastal dune habitats in Florida where they create carpets of plants, crowding out native species.” So, you should always look up which kalanchoe species are safe versus which ones are invasive for your location before you plant them out in your flower beds. Of course, you can also take steps to contain them, like deadheading them rather than letting them go to seed. Keeping them indoors as houseplants also is a good way to ensure that invasive species do not spread.