There’s something truly magical about witnessing a butterfly bush in full bloom, its elongated clusters of vibrant flowers swaying gently in the breeze.
By midsummer, butterfly bushes (Buddleia davidii) are in full bloom producing graceful wands of flowers and nectar that adult butterflies (monarchs and swallowtails) and other wildlife pollinators can’t resist.
These fast-growing shrubs are suitable for planting island beds, cottage gardens, perennial borders, or wherever their loose growth habit won’t detract from a particular landscape design you’d like to achieve.
To ensure their optimal growth and to attract a multitude of butterflies, I always made sure to plant them in a sunny spot. Over the years, I’ve found that the more sun they receive (around six hours a day) the more butterflies they attract. It’s a delightful sight when the butterflies flutter around, drawn by the nectar-rich blooms.
When it comes to soil, butterfly bushes are quite accommodating. In my garden, I’ve planted them in various soil types, but I always make sure that the soil was well-draining and enriched with organic matter.
By amending the soil with compost or well-rotted manure, you’ll provide them plants with the perfect foundation for robust growth.
The bushes are low-maintenance, allowing even weekend gardeners to appreciate their beautiful blooms and the butterflies they attract. However, some caution is required because this plant self-seeds so quickly that it is designated a noxious weed in some areas.
In the spring, butterfly bush is commonly planted from potted nursery starts or from seeds. It is a particularly fast-growing plant that normally matures within a single growing season.
Butterfly bushes tend to sprawl as they grow up to 10-12 feet tall, although you can opt for a dwarf variety that offers a neater, more compact growth habit if you are going for a more groomed look.
Botanical Name: Buddleja davidii
Common Name: Butterfly bush
Plant Type:Shrub, perennial
Hardiness Zones:5 – 9 (USDA)
Sun Exposure:Full sun
Soil Type:Moist, well-drained soil
Soil pH: 6.0 – 7.0 (Acidic, neutral)
Height: Up to 3 – 12 feet tall
Flower Colors: Purple, pink, white, blue, yellow
Native Area: Asia
Quick Guide: Planting, Growing & Caring for Butterfly Bush
- Butterfly bushes thrive in full sun, so ensure they receive at least six hours of direct sunlight each day.
- They prefer well-draining soil that retains moisture without becoming waterlogged. Amend the soil with organic matter to improve drainage and fertility.
- Regular pruning is essential to maintain the shape and vigor of your butterfly bush. Prune in early spring before new growth emerges, removing dead, damaged, or weak branches.
- While butterfly bushes are generally resistant to pests and diseases, keep an eye out for common issues such as aphids and nematodes.
Butterfly Bush Plant Care
Butterfly bush, also known as summer lilacs, is a fast-growing perennial with arching stems and masses of long spiked flowers that bloom from summer to autumn. Although low maintenance, this plant must be pruned -preferably in early spring.
Butterfly bush plants are hardy to zone 5 and remain as an evergreen from zone 8 south. This plant grows up to 5-10 feet tall and displays mainly purple and pink flowers. This plant’s growth appears on new wood, so pruning can be done until the new wood is ready to grow in spring. You must be patient with the butterfly bush since the shrub might not leave in the spring until after other perennials.
Butterfly bushes thrive when planted in early spring or late fall, but you can put them in your garden in mid-summer if you keep them well-watered. Planting butterfly bushes in an island bed is a great way to encourage these beautiful insects to your garden.
Butterfly bush plants are mainly grown for their extensive panicles of beautifully colored flowers and their ability to attract beneficial insects and butterflies. They bloom in spring-summer, but their naturally attractive shrub shape and evergreen foliage keep this plant interesting even when it’s not blooming. These hardy plants can tolerate different growing conditions.
Despite its common name, butterfly bush is not a ‘host plant’ for butterflies because it does not support butterfly reproduction and lifecycle. Caterpillars do not feed on butterfly bushes; instead, it offers nectar to adult butterflies in the same way that many flowers do.
If you have a butterfly bush, add native host plants like milkweed, aster, and dill if you want the butterflies to stay.
The butterfly bush is a sun-loving marvel, thriving and putting on its best show when basking in the warm embrace of sunlight.
To truly unleash its full potential, this enchanting shrub requires a generous dose of sunshine, meaning approximately six hours or more of direct sunlight each day. If grown in shady conditions, it will become sparse and weedy.
The butterfly bus thrives in any average soil as long as it receives enough moisture and is well draining and retains moisture without becoming waterlogged.
Soil that is too compacted or heavy in clay can hinder proper drainage, leading to waterlogged roots and potential root rot. This plant prefers a 6.0 to 7.0 pH soil -slightly acidic to neutral.
Proper watering is crucial for these resilient shrubs. While butterfly bushes are known for their drought tolerance, I’ve learned that regular watering during hot summer months is essential to keep them happy and healthy.
Deep, thorough watering, ensuring the moisture reaches the roots, has always been my practice. This plant thrives on ½ inch of water by irrigation or rain each week. However, I’ve also been cautious not to overwater or allow the soil to become waterlogged, as this can lead to root rot which will prevent flower buds from forming.
Temperature and Humidity
As a semi-evergreen, this plant likes warm climates but can tolerate cold climates if they don’t drop below 20°F and do not go over 90°F; anything above this temperature can cause flower buds to stop developing.
This plant likes a moist but not soggy environment. When it is first planted, it should be watered once a week until it establishes. Once the roots have taken hold, the plant will mostly be drought-tolerant.
Mulch with a couple of inches of pine straw or crushed bark to keep weeds away and retain moisture. Allow no mulch to get into contact with the stems since this might induce rot.
This beautiful evergreen needs little fertilizer besides a thin compost layer spread over the root zone every spring. And so, I personally apply a balanced fertilizer in early spring, just before new growth emerged.
Whether I opted for slow-release granules or a liquid fertilizer diluted as per the instructions, I always remember that moderation is key. I’ve learned that a little goes a long way, as excessive fertilization can result in leggy growth and diminished flowering.
Old flower spikes of this plant should be removed promptly after flowering to stimulate continuous blooming right up to frost, reducing the self-seeding chances.
Pruning has played a vital role in maintaining the health and shape of my butterfly bushes. Each year, during late winter or early spring when they were still dormant, I take the time to prune back the previous year’s growth.
Cutting them back to about 12 to 24 inches above the ground stimulates new growth and gets a more compact and bushy form. This annual pruning ritual will reward you with abundant blooms and a visually appealing shrub.
It’s important to also deadhead when they start to wither so that it can stop this invasive plant from spreading its seeds.
What is the Difference Between Butterfly Bush and Butterfly Weed?
Even though the common names are similar, these are two different kinds of plants. However, both have a good reputation for attracting butterflies and other pollinators, which is why they have similar common names.
Butterfly weed (Asclepias tuberosa) is typically a shorter plant, rarely exceeding 3 feet in height. Plus, it is considerably more cold-resistant than butterfly bush, being appropriate for zone 3. Instead of spikes, the orange or yellow blooms create clusters.
Butterfly weed is a typical roadside wildflower, however there are varieties available for landscaping usage. It’s a plant that is native to North America, so it is not an unwanted foreign plant. This makes it a good choice for people who like to grow native plants.
How to Plant and Grow Butterfly Bush
How to Plant Butterfly Bush
Choose a location in your garden that receives full sun for at least six hours a day. Butterfly bushes thrive in sunlight, which is essential for their growth and abundant flowering.
Make sure that the spot you choose has enough space for the mature size of the plant, as this deciduous shrub can grow quite large.
Butterfly bushes prefer well-draining soil that is enriched with organic matter. Prior to planting, loosen the soil in the designated area using a garden fork or tiller. Remove any weeds or grass and incorporate compost or well-rotted manure into the soil. This helps improve its texture, fertility, and moisture retention capabilities.
How to Propagate Butterfly Bush
Since this bush spreads so readily by itself, butterfly bush propagation is rare. However, collecting seed heads will give you plenty of viable seeds to replant if you want to propagate your butterfly bush.
Seed propagation is impossible if you own a sterile seedless variety of butterfly bush in your garden. If you have a non-patented seedless variety, you can propagate by root branching cuttings during summer.
Here’s how to do it:
- Using clean, sharp pruners, cut a 4-6 inch segment from a healthy branch tip – ensure that the cut is made just below a healthy bud.
- Remove the bottom leaves, leaving a couple at the top.
- Dip the cut ends of the selected stems in a rooting hormone powder or gel. The rooting hormone contains growth regulators that stimulate root formation and improve the chances of successful propagation. Shake off any excess hormone to avoid excessive concentrations.
- Next, prepare a well-draining medium with peat moss and perlite or vermiculite. This mixture retains moisture while providing adequate aeration for root development. Moisten the medium before planting the cuttings. Plant it in a small pot filled with this mixture and moisten it.
- Place the plant in a plastic bag to keep the moisture and place it in a bright location (avoid direct sunlight).
- Be patient, as root development takes time. Monitor the moisture level in the propagation medium and ensure it remains consistently moist but not waterlogged. Avoid overwatering, as excess moisture can lead to rotting. Check for signs of new growth, which indicate successful rooting.
- New roots should develop in 3-6 weeks, you can tug lightly on the stem, and if you feel resistance, it is ready. When this happens, transplant the cutting into a bigger container or the garden.
Common Pests and Plant Diseases for Butterfly Bush
There are no specific pests or diseases associated with butterfly bush, although spider mites and nematodes can be an issue in southern regions. You can use pyrethrin-based insecticides or horticultural oil to spider mites, but for nematodes, there’s no effective treatment, so affected plants should be pruned and destroyed.
Melissa Pino is a biologist, master gardener, and regular contributor for Planet Natural. Melissa's work focuses on promoting environmentally-friendly practices, helping people create healthy gardens and finding ways to achieve overall health and wellness.