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At a glance
| Botanical name | Buddleja davidii (also spelled Buddleia) |
|---|---|
| Family | Scrophulariaceae |
| Type | Deciduous to semi-evergreen shrub; dieback shrub in cold zones |
| USDA zones | 5–9 (often dies to the ground in 5–6) |
| Mature size | 6–12 ft tall and 4–15 ft wide; Lo & Behold 'Blue Chip' 1–2.5 ft |
| Bloom | Summer, roughly June to September, on new growth |
| Light | Full sun (6+ hours) |
| Soil | Average, well-drained; drought tolerant once established |
| Native range | Tibet and central and southern China |
| Invasive status | Noxious weed in WA and OR; naturalized and spreading in parts of the East |
| Deer | Rarely browsed (NC State lists deer resistance) |
What butterfly bush is
Butterfly bush is an arching, fast-growing shrub from China with gray-green, lance-shaped leaves and long, dense, fragrant flower spikes in purple, lavender, pink, white or dark red. NC State Extension describes the species as growing 6–12 feet high and 4–15 feet wide at a rapid rate, native to Tibet and central and southern China, and blooming from June to September.
The flowers are a heavy nectar source for adult butterflies, bees and other pollinators through summer, which is why it is sold as a pollinator plant. Nectar is only half of what butterflies need, though: caterpillars need host plants, which is where native alternatives come in (more below).
"Buddleia" and "Buddleja" are the same plant; Buddleja is the botanically correct spelling, and Buddleia remains common in the nursery trade.
Is butterfly bush invasive?
It depends on where you live, and the answer is yes in more places than nursery tags suggest.
| Region | Status | Source |
|---|---|---|
| Washington | Class B noxious weed; quarantined, except accepted sterile cultivars (under 2% viable seed) | Washington State Noxious Weed Control Board |
| Oregon | Covered by the state noxious weed quarantine; only ODA-approved seedless cultivars may be propagated or sold | Oregon Department of Agriculture |
| Maryland | Invasive and spreading: reported in 4 counties in 2019 and 8 more by 2025; colonizes stream banks and disturbed sites | University of Maryland Extension |
| Tennessee | Ranked an emerging invasive threat | Tennessee Invasive Plant Council |
| North Carolina | Listed invasive in the Mountain and Piedmont regions by the NC Invasive Plant Council | NC State Extension |
| Mid-Atlantic states | Aggressive spreading reported | NC State Extension |
| Pacific Northwest, Northeast, Hawaii, Puerto Rico | Naturalized outside gardens | USDA NRCS |
Butterfly bush spreads by enormous numbers of tiny, wind-dispersed seeds that colonize stream banks, roadsides, rail lines and disturbed ground. Oregon State University Extension advises gardeners who keep seed-spreading plants such as purple butterfly bush to deadhead aggressively before seeds mature, and to bag invasive plant material for the trash rather than composting it, since most home compost piles do not get hot enough to kill seeds.
What to do: if you live in the Pacific Northwest or near natural areas in the East, plant a sterile cultivar or a native shrub instead. Rules change, so check your state's current noxious weed list before buying.
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Annual spring cut-back means a lot of stems; a sharp bypass pruner handles everything up to finger thickness cleanly. See how we chose it.
Sterile and low-seed cultivars
Plant breeders have developed butterfly bushes that set little or no viable seed. The best documented is the Lo & Behold series from NC State University. NC State Extension describes Lo & Behold 'Blue Chip' as having very low fertility, effectively sterile, and approved for sale in Oregon and Washington. It stays roughly 1–2.5 feet tall and wide and suits small beds and containers.
The Oregon Department of Agriculture publishes a list of approved seedless cultivars, which must produce 2 percent or less viable seed; it includes 'Blue Chip', 'Blue Chip Jr.', 'Ice Chip', 'Purple Haze', 'Asian Moon' and several Flutterby selections. It is a useful public screen of "seedless" claims and is worth checking even outside Oregon. Treat "non-invasive" on a plant tag as marketing unless a state agency or university trial backs it up, and keep deadheading any cultivar whose seed set is unknown.
Native alternatives for butterflies
If you want butterflies, a native shrub can do the nectar job and also feed caterpillars and native bees. Good options with long summer bloom in full sun:
| Native plant | Type | Why it works |
|---|---|---|
| Buttonbush (Cephalanthus occidentalis) | Shrub | Fragrant white pincushion flower heads June to September; needs moist to wet soil |
| Summersweet (Clethra alnifolia) | Shrub | White late-summer flower spikes with high-quality nectar; full sun to part shade, moist soil |
| New Jersey tea (Ceanothus americanus) | Small shrub | Fragrant early-summer flowers; drought tolerant; caterpillar host for spring and summer azure butterflies |
| Joe Pye weed (Eutrochium spp.) | Tall perennial | 4–7 ft perennial for moist soil; flowers attract bees and butterflies |
| Milkweeds (Asclepias spp.) | Perennial | Nectar plus the monarch's only caterpillar host; see milkweed care |
Plant notes are from NC State Extension's Plant Toolbox. Combining nectar plants with caterpillar host plants is the core of starting a pollinator garden, and the regional lists in best native shrubs for wildlife help match natives to your area.
Zones, sun and soil
- Zones 5–6: NC State Extension notes the shrub dies back to the ground here but makes vigorous growth in spring, so it is grown much like a perennial.
- Zones 7–9: stems are more likely to survive winter; in zones 8 and warmer, USDA NRCS advises a spring trim of the weeping side branches rather than a full cut-back.
- Sun: full sun, 6 or more hours of direct light a day (NC State Extension).
- Soil: moist, well-drained soil. NC State Extension says it adapts to most soils but does not tolerate wet soil, recommends amending clay to avoid poor drainage, and notes root rot where soil stays consistently wet. It also lists drought and heat among the challenges it resists.
Planting butterfly bush
Plant in spring after the danger of frost, or in early fall in mild climates, so roots establish before winter. In zones 5–6, spring planting gives the best survival.
- Choose a full-sun spot with sharp drainage and room for the mature width.
- Dig a hole as deep as the root ball and wider than it; in clay, amend the area so water does not stand around the roots.
- Backfill, water thoroughly, and mulch lightly, keeping mulch off the crown.
- Water regularly through the first summer; after that, water only in prolonged drought.
When and how to prune butterfly bush
Butterfly bush flowers on the current season's growth, so hard spring pruning produces more and better blooms rather than fewer.
- Timing: late winter or early spring, as buds begin to swell at the base. NC State Extension recommends early-spring pruning to control growth and encourage large flowers, and notes the best flowers follow severe pruning in late winter.
- Height: in zones 5–6, USDA NRCS advises cutting back to about a foot high in late winter; cut just above a pair of healthy buds.
- Clean-up: remove dead stems at the base and thin out the oldest, weakest stems on established clumps.
- Dwarf types: follow the grower's instructions, since compact cultivars may need less severe cutting.
Deadheading: remove spent flower spikes through the season. USDA NRCS advises removing flowers before they set fruit, both to extend bloom and to limit unwanted seeding; Oregon State University Extension likewise says to deadhead seed-spreading butterfly bush aggressively, well before seeds mature. NC State Extension notes deadheading the sterile Lo & Behold types encourages rebloom but is otherwise not necessary. Bag the spent spikes for the trash.
The same "prune in spring, blooms on new wood" logic covers other summer-flowering shrubs; see how to prune flowering shrubs.
How to overwinter a butterfly bush
- Don't cut it back in fall. Leave the stems standing over winter and prune in late winter, when you can see exactly what survived. In zones 5–6, USDA NRCS suggests mulching in fall.
- Keep winter soil from staying wet. NC State Extension links consistently wet soil to root rot, so a well-drained site is the most important winter protection.
- In zones 5–6, be patient in spring. Plants killed to the ground regrow from the crown, often late. Wait until other shrubs have leafed out before deciding a plant is dead.
- Skip late feeding. Fertilizer in late summer pushes soft growth that winter kills.
Pests, problems and wildlife
NC State Extension reports no serious insect or disease problems but notes spider mites can become a problem during drought. USDA NRCS adds caterpillars, weevils, mullein moth, fungal leaf spot and dieback as things to watch, especially on stressed plants; keep plants watered in heat and see spider mites on outdoor plants if leaves turn stippled and bronze. Root rot follows poorly drained soil.
NC State Extension lists deer, rabbits, drought, heat and salt among the challenges the species resists, and lists deer resistance for 'Blue Chip' as well. For overall deer strategy, see starting a deer-resistant garden.
Common mistakes
| Mistake | Why it matters | Do this instead |
|---|---|---|
| Planting the seeding species near woods, streams or open land | Wind-blown seed spreads it into natural areas | Plant a sterile cultivar or a native shrub |
| Cutting it back in fall | You remove stems before you can see what survived winter | Prune in late winter or early spring as buds swell |
| Leaving it unpruned for years | Old woody stems produce short, sparse flower spikes | Cut back to about 12 inches every spring |
| Planting in part shade or wet clay | Shade means sparse bloom; wet soil means root rot | Full sun and sharp drainage; amend clay for drainage |
| Composting deadheaded flower spikes | Home compost rarely gets hot enough to kill the seed | Bag spent spikes for the trash |
Frequently asked
When should you prune a butterfly bush?
Prune in late winter or early spring, as buds start to swell near the base. Cut stems back to about a foot high, as USDA NRCS advises for cold zones; the plant blooms on new growth, and NC State Extension notes the best flowers follow severe late-winter pruning. Avoid fall pruning.
How do you overwinter a butterfly bush?
Leave the stems standing through winter and wait until spring to prune. Make sure the soil drains well, since wet soil leads to root rot. In zones 5 and 6 the top often dies back and the plant regrows from the crown, sometimes late in spring.
Is butterfly bush invasive?
In some places, yes. Washington lists Buddleja davidii as a Class B noxious weed and Oregon allows sales of only approved seedless cultivars; NC State Extension reports it is listed invasive in North Carolina's Mountain and Piedmont regions and spreading aggressively in Mid-Atlantic states, and University of Maryland Extension documents its spread there. Where it spreads, plant a sterile cultivar or a native shrub instead.
How big does a butterfly bush get?
The common species grows 6 to 12 feet tall and 4 to 15 feet wide, per NC State Extension. In zones 5 and 6 it dies back to the ground and regrows each spring. Dwarf types such as Lo & Behold 'Blue Chip' stay about 1 to 2.5 feet.
Should you deadhead a butterfly bush?
Yes, for seeding types. USDA NRCS notes that removing flowers before they set fruit extends bloom and limits unwanted seeding. On sterile cultivars such as 'Blue Chip', NC State Extension says deadheading encourages more blooms but is otherwise not necessary.
How much sun does a butterfly bush need?
Full sun, meaning six or more hours of direct sun a day, per NC State Extension. Plants bloom best with plenty of light.
Is butterfly bush deer resistant?
Generally yes. NC State Extension lists deer resistance for both the species and Lo & Behold 'Blue Chip'. No plant is deer-proof when deer are hungry, so protect new plantings where pressure is heavy.
When does butterfly bush bloom?
Through summer, roughly June to September per NC State Extension, on the current season's growth. Removing spent flowers extends the bloom season.
Sources
- Buddleja davidii (butterfly bush), NC State Extension Gardener Plant Toolbox
- Buddleja Lo & Behold 'Blue Chip', NC State Extension Gardener Plant Toolbox
- Butterfly bush, Washington State Noxious Weed Control Board
- Butterfly bush approved cultivars, Oregon Department of Agriculture
- Invasive species: what gardeners need to know (EM 9035), Oregon State University Extension
- Invasives in your woodland: butterflybush (updated 2025), University of Maryland Extension
- Plant details: Buddleja davidii, Tennessee Invasive Plant Council
- Orange eye butterflybush plant fact sheet, USDA NRCS