The butterfly bush is a fast-growing garden shrub that produces large, loose clusters of flowers called panicles. The rainbow variety has been specially bred to produce multicolored blossoms on each panicle.
Plant in spring or fall
Choose a location with good, well-drained soil that gets lots of sun. Dig a hole twice the diameter of the potting container, and mix some compost in with the soil. Plant so the top of the rootball is level with the soil's surface.
Give it lots of room
A rainbow butterfly bushes can grow up to 10 feet in height with as much as an 8-foot spread. Space new plants from 6 to 10 feet apart. Water new plants thoroughly.
Remove spent flowers
The butterfly bush grows quickly and should bloom abundantly even in the first year. Deadheading the old panicles encourages new ones to grow.
Cut back in the late winter
Even if the weather is warm enough for the stems to survive, cut the entire shrub back to 12 to 24 inches from the ground in late winter. Add a layer of mulch around the stems. Yearly pruning encourages abundant growth and maximum flower production.
Prune yearly to encourage growth
In cold climates, the butterfly bush behaves as a perennial and dies back to the root. Spread mulch around the trunk to sustain the shrub through the winter. In warm climates, butterfly bushes grow to full-sized trees with rugged trunks. Pruning the shrub all the way back every year prevents it from becoming unmanageably large.