How-to Guide
How to Grow Butterfly Bush
The short answer
Butterfly bush (Buddleja davidii) is a fast, sun-loving shrub that blooms on new wood, so care is simple: plant in full sun and well-drained soil, cut it back hard in early spring before growth begins, and deadhead spent flower spikes through summer to keep blooms coming and stop seed set.
Before planting, check its status where you live. Buddleja davidii self-seeds prolifically and is classified as invasive in parts of the US, notably the Pacific Northwest, where it invades riverbanks and disturbed ground; Penn State Extension recommends choosing seedless/sterile cultivars or native alternatives instead of the straight species.
What butterfly bush is
Butterfly bush is a vigorous deciduous shrub, typically 4-10 feet tall depending on cultivar, with long cone-shaped flower spikes in purple, pink, white, or blue that draw adult butterflies all summer. It grows fast, blooms the first year, and shrugs off heat and drought once established.
Note the ecological caveat: it feeds adult butterflies nectar but is not a host plant for their caterpillars, so extension programs suggest pairing it with, or replacing it by, native shrubs that support the full butterfly life cycle.
The invasive question
Buddleja davidii produces enormous quantities of viable seed, and escaped plants have naturalized in several regions; it is regulated as invasive in Oregon and Washington among others. Penn State Extension's guidance: avoid the straight species, and if you want the look, use modern sterile or near-sterile cultivars bred to set little to no viable seed, or plant native alternatives such as buttonbush or summersweet.
⚠ Check your state's invasive plant list before buying a butterfly bush. Where it is regulated, choose approved sterile cultivars or native alternatives.
Planting butterfly bush
- 1Full sun, drained soil — Give it at least 6 hours of direct sun and well-drained soil; wet winter soil is the most common killer.
- 2Give it room — Many cultivars reach 4-10 feet in a single season after cutback, so space generously or pick a dwarf series for small beds.
- 3Water to establish, then ease off — Water regularly the first season; established plants are quite drought tolerant and need no rich feeding.
Pruning and deadheading
Butterfly bush blooms on new wood, so the standard routine is a hard cutback in early spring, before new growth gets going, which keeps the shrub compact and maximizes flowering wood. In cold-winter areas the top often dies back anyway and the plant regrows from the base.
Through summer, deadhead spent flower spikes regularly. It keeps new spikes coming and, just as important, prevents the plant from ripening and scattering seed.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- Penn State Extension — Avoiding Invasives: Butterfly Bush — Buddleja davidii's invasive behavior, the recommendation to use sterile cultivars or native alternatives, and its limitation as nectar-only (not a larval host)
- University of Arkansas Cooperative Extension — Butterfly Bush — Culture: full sun, well-drained soil, blooms on new wood, hard early-spring pruning, deadheading to prolong bloom