Butterfly bushes (Buddleia davidii) are grown for their long panicles of colorful flowers and their ability to attract butterflies and beneficial insects. They bloom in spring and summer, but the naturally attractive shape of the shrub and evergreen foliage keep the bush interesting, even when it is not in bloom.
These tough plants tolerate a variety of conditions and are hardy in USDA plant hardiness zones 5 through 9. Find out more about butterfly bush planting and care.
Butterfly Bush Planting
Planting a butterfly bush in an optimum location minimizes the time you’ll spend on maintenance. Choose a sunny or partly shaded area where the soil is well-drained. Soil that is constantly wet encourages rot. When planted in good quality garden soil, a butterfly bush rarely needs fertilizer.
Give your butterfly bush plenty of room. The plant tag will tell you the mature size of the cultivar you have chosen. Although butterfly bushes tolerate severe pruning to maintain a smaller size, you can reduce the time you’ll spend pruning by planting it in a location with plenty of room for the plant to develop its natural size and shape. Butterfly bushes grow from 6 to 12 feet (2-4 m.) tall with a spread of 4 to 15 feet (1-4.5 m.).
How to Care for a Butterfly Bush
Butterfly bush care is easy. Water the shrub slowly and deeply during prolonged dry spells so that the soil absorbs the water deep into the root zone.
The plants don’t need fertilization unless grown in poor soil. Fertilize with a 2 inch (5 cm.) layer of compost over the root zone or scratch in some general-purpose fertilizer if you need to enrich the soil. Cover the root zone with a 2 to 4 inch (5-10 cm.) layer of mulch. This is particularly important in cold climates where the roots need winter protection.
The most labor-intensive part of caring for butterfly bushes is deadheading. In spring and summer, remove the spent flower clusters promptly. Seed pods develop when the flower clusters are left on the plant. When the pods mature and release their seeds, weedy young plants emerge. The seedlings should be removed as soon as possible.
Young shrubs that are cut off at ground level may re-emerge, so remove the roots along with the top growth. Don’t be tempted to transplant the seedlings into other parts of the garden. Butterfly bushes are usually hybrids, and the offspring probably won’t be as attractive as the parent plant.
Problems with Butterfly Bushes
Problems with butterfly bushes include root rot and the occasional caterpillar. Planting the shrub in well-drained soil usually eliminates the chances of root rot. The symptoms are yellowing leaves, and in severe cases, twig or stem dieback.
Any time you grow a plant that attracts butterflies, you can expect caterpillars. In most cases the damage is minimal and you will have to stand close to the shrub to notice it. It’s best to leave the caterpillars alone unless their feeding activity does substantial damage to the shrub.
Japanese beetles sometimes feed on butterfly bushes. Using insecticides to control Japanese beetles is usually ineffective, and more likely to destroy the abundance of beneficial insects attracted to the shrub than the beetles. Use traps and handpick the insects, and treat the lawn for grubs, which are the larval form of Japanese beetles.