How to Grow Butterfly Bush

Light: Butterfly bushes grow and flower best in full sun. They will grow fine in part shade, especially in warmer climates, but their flowering may be reduced.

Soil: Butterfly bushes are not particular about the soil conditions, as long as it drains well. Poorly-drained soils can cause root rot.

Spacing: Space butterfly bushes 5 to 10 feet apart depending on the variety. Plant dwarf varieties closer together.

Planting: Plant butterfly bushes in early spring or fall. If planting in midsummer in hot climates, be sure to provide plenty of water and even some afternoon shade.

Growth Habit: Butterfly bushes grow 2 to 10 feet tall and wide. The species versions grow the largest and produce the most flowers. New breeding has created many dwarf varieties that fit better in the landscape.

This woody shrub can die back to the ground in climates colder than USDA zone 5. In warmer areas, it regrows consistently each spring from old wood. The leaves can be thin, narrow and silver-green colored. Some varieties have green and yellow variegated leaves. The fragrant flowers form on 5- to 12-inch-long clusters in white, blue, lavender, pink, orange, purple, yellow with many intermediate shades.

Staking: Butterfly bushes grown in full sun have strong-enough stems that will hold the flower clusters upright and will not need staking. Tall varieties grown in part shade may have leggy and floppy stems that benefit from a cage of chicken wire wrapped around the plant, or staking of individual branches with a metal or wooden stake before flowering.

Watering: Butterfly bushes grow best in moist, well-drained soils. Keep the soil consistently moist all summer for best growth and flowering especially during hot, dry weather.

Fertilizing: Amend the soil at planting time with compost. Each spring, add a 2- to 3-inch thick layer of compost around the base of the plants. The compost not only feeds the plant roots, but also enhances the organic matter in the soil so that it stays consistently moist.

Mulching: Mulch in early spring with a 2- to 3-inch thick layer of shredded bark mulch or leaf mold to prevent weed growth and to conserve soil moisture. Keep the mulch away from the branch stems and crown to avoid rot diseases.

Trimming & Pruning: Deadhead (snip off) spent butterfly bush flowers after they start to fade to tidy up the plant, encourage more blossoms to form, and prevent self-sowing. Prune butterfly bushes in early spring to remove winter-injured, diseased and broken branches. In cold climates, the branches may die back to the root system during harsh winters. Wait until late spring to decide if the branch is dead. Butterfly bushes can be slow to leaf out in spring. If dead, prune back to the ground.

For taller butterfly bushes with healthy growth, prune all the branches back to one foot off the ground in early spring to stimulate new growth and more flowering.

Dividing & Transplanting: Butterfly bushes can be divided and transplanted in early spring or fall. Moisten the soil around the shrub and dig up the clump. Separate sections of roots with some shoots and replant in a similar location in compost amended soil.

Butterfly bushes can also be propagated by stem cuttings. In late spring and early summer take a 4- to 6-inch long cutting of a new stem once the stem is sturdy enough to not bend. Dip the cut end in rooting hormone powder and stick the cuttings in a pot filled with moistened potting soil. Keep the cutting out of direct sun and well-watered.

Butterfly bushes can be grown from seed, but they will take a long time to reach a flowering stage, so division or stem cuttings are better routes to making more plants.

Pests/ Disease: Butterfly bushes are relatively pest-free plants. Spider mites can attack the foliage during periods of summer heat and drought. During wet periods, rot diseases can attack the root system especially on poorly drained soils.

The biggest problem with butterfly bushes in northern areas is not surviving the winter. To protect butterfly bushes from harsh winters in the northern end of its range, add a 4- to 6-inch thick layer of bark mulch over the root system in late fall to protect the roots from winter temperatures and winds.