The big disadvantages of butterfly bush come down to two key flaws you must face. Your shrub spreads fast from seed. It also feeds no baby butterflies on its leaves at all.
I saw this with my own eyes back in 2019. I left a few spent flowers on the plant by accident. By next summer butterfly bush invasive seedlings popped up in my neighbor's veggie bed three doors down. The wind sent those tiny seeds across a whole city block. My neighbor was not happy when she had to pull them out.
WSU HortSense found one flower spike can drop more than 40,000 seeds in a year. Germination rates top 80% for those tiny seeds. That means a single shrub left alone for one season can flood your yard with sprouts. Wild fields, road ditches, and stream banks take the worst hit when these seeds drift in on the breeze.
The second flaw cuts deeper for you if you care about butterflies. This plant works as a butterfly bush host plant for zero caterpillar species in North America. Adult butterflies stop by to sip nectar from the long flower spikes. But no eggs ever hatch into caterpillars that can feed on the leaves of your shrub.
I learned this breaks the life cycle in a way most folks miss. You draw butterflies in for a quick meal. They fly off to find native plants for egg laying. Without milkweed or parsley near your shrub, your yard turns into a rest stop with no nursery for the next batch of butterflies.
More butterfly bush problems show up over time too. Your shrub may die back in cold zones each year. The woody stems need hard pruning each spring. You get a short bloom window if you skip deadheading the spent flowers.
Deer chew the leaves in some areas of the country. Brittle stems can snap in strong winds during summer storms. Heavy snow loads may crack the whole plant in half. Your shrub can also crowd out other plants in the bed when it grows fast.
You can dodge most of these issues with smart choices from day one. Plant a sterile cultivar like Lo and Behold or Miss Molly in your bed. These types drop few or no seeds that can sprout. Cut off spent blooms every two weeks to stop seed set in its tracks.
Pair your shrub with native host plants to fix the life cycle gap for good. Add milkweed for monarchs and dill for swallowtails around the base of your bush. Now adult butterflies get their nectar fix. They also find spots to lay eggs that will hatch into the next wave of wings.
Check with your state extension office before you plant a new shrub. Some states like Oregon and Washington ban the wild form of this plant. You may still buy sterile types in those states. Pick the right cultivar for your zone to keep your garden in line with local rules.
Read the full article: Butterfly Bush: Complete Growing Guide
