Designating a plant as invasive is usually a sad occasion because they are almost always plants that most people do love dearly, and have been moved around by gardeners a great deal, and then escaped into wild areas. When non-native escapees are so successful that they displace native plant populations, they are designated as invasive. Sterile means a plant can't make seeds. Why there would ever be any BB's for sale that are not sterile is a mystery to me. I'd recommend a sterile BB to anyone who gardens where they are hardy.