The Real Butterfly Bush

by Tom Hewitt

They don’t call buddleia “butterfly bush” for nothing. Trouble is, here in south Florida Buddleia davidii behaves as a short-lived perennial. It starts out healthy enough, but its flower spikes get smaller and smaller until the plant dies.

I’ll never quit buying buddleias, but now I have a new favorite that takes on the title of butterfly bush. Tropical aster (Bartlettina sordida) only blooms for several weeks each winter, but it rivals buddleias for attracting butterflies.

I once stood in front of one bush and watched five different species nectaring at one time! This was in addition to skippers, bees and other pollinators. The flowers of tropical aster resemble blue ageratums on steroids and have a subtle scent reminiscent of lilacs.

The only downside to tropical aster is that it gets so darn HUGE. It’s nothing for one plant to get 8 by 12 feet. But you can cut them back drastically after flowering to keep them in scale. In the butterfly garden, I selectively prune them and let just a few branches ramble until they bloom.

But tropical asters look best where they’re allowed to do their things. They make great background material for a large butterfly garden. They have a naturally rounding habit and huge, heart-shaped leaves.

Most butterfly plants like full sun. But tropical asters prefer partial shade, at least during the hottest part of the day. They’re used to growing in the cloud forests of Mexico, and like moist, well-draining soil that’s high in organic matter.

Tropical asters (listed for zone 9-11) can be hard to find in garden centers. But if you know someone who has one, you can start new plants from cuttings. We always carry them in the nursery at Mounts Botanical Garden in West Palm Beach (www.mounts.org). Trouble is, we always sell out when they’re in bloom. I wonder why?

 © 2014 Tom Hewitt. Originally published in Florida Gardening, Jun / Jul 2014. Reprinted by permission. All rights reserved.