Yes, your beloved butterfly bush is INVASIVE. Sorry!
Originally from China, this guy has tiny seeds that are easily dispersed by the wind. It can easily escape and displace native plants. Even those bread to be "sterile" can be cross-pollinated by non-sterile plants and develop viable seeds.
So what do you do if you have a butterfly bush and don't want to remove it? Be vigilent about deadheading. Cut those flowers off as soon as they start to fade. Pull any seedlings that you spot on yours and surrounding properties.
But let's think about why you planted that butterfly bush in the first place... Did you just like the plant, or did you want it to attact butterflies to your garden? If you love the plant, then keep it and deadhead like crazy. But know that you are not providing any value to those butterflies. Yes, they can eat the nectar all day long and look beautiful doing it. But they cannot lay their eggs on this plant. It does not provide habitat or sustenance for the caterpillars. In fact, not a single North American caterpillar can eat it's leaves. There are so many great choices of shrubs to plant instead! Clethra alnifolia (Summersweet - coming to a #nativeplantrecommendation post soon!) or Cephalanthus occidentalis (buttonbush).
So what do you think? Will you consider replacing your butterflybush, or will you be doing all that deadheading?
📷: Uschi Dugulin from Pixabay
Sources: DNCR Native Plant Fact Sheet,
"Bringing Nature Home" by Doug Tallamy