By: Mary H. Dyer, Credentialed Garden Writer
If you’re attempting to grow butterfly bush (Buddleja davidii) in USDA planting zone 4, you have a challenge on your hands, as this is slightly chillier than the plants really like. However, it really is possible to grow most types of butterfly bushes in zone 4 – with stipulations. Read on to learn about growing butterfly bushes in cold climates.
How Hardy is Butterfly Bush?
Although most types of butterfly bush grow in zones 5 through 9, some tender types need milder winter temperatures found in at least zone 7 or 8. These warm climate butterfly bushes won’t survive a zone 4 winter, so read the label carefully to be sure you’re purchasing a cold hardy butterfly bush suitable for a minimum of zone 5.
Reportedly, some of the Buddleja Buzz cultivars may be more appropriate butterfly bushes for zone 4 growing. While most sources indicate their hardiness as zone 5, many are hardy from zones 4-5.
It may sound like a mixed message, but you can, in fact, grow a butterfly bush in zone 4. Butterfly bush is evergreen in warm climates and tends to be deciduous in cooler climates. However, zone 4 is downright cold, so you can expect that your butterfly bush will freeze to the ground when temperatures plummet. That being said, this hardy bush will return to beautify your garden in spring.
A thick layer of straw or dry leaves (at least 6 inches or 15 cm.) will help protect the plants during the winter. However, butterfly bushes are late to break dormancy in cold climates, so give the plant a little time and don’t panic if your butterfly bush looks dead.
Note: It’s important to note that Buddleja davidii can be extremely weedy. It has the potential to be invasive anywhere, and so far has naturalized (escaped cultivation and become wild) in at least 20 states. It is a serious problem in the Pacific Northwest and sale of butterfly bush is prohibited in Oregon.
If this is a concern in your area, you may want to consider the less invasive butterfly weed (Asclepias tuberosa). In spite of its name, butterfly weed isn’t overly aggressive and the orange, yellow and red blooms are great for attracting butterflies, bees, and hummingbirds. Butterfly weed is easy to grow and, more importantly, will easily tolerate zone 4 winters, as it is hardy to zone 3.
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The Ultimate Butterfly Bush Care Guide from Proven Winners ®
Butterfly bush is hard to beat for sheer flower power. These easy, sun-loving shrubs come in an array of rich colors, bloom continuously from summer to fall, and attract butterflies and hummingbirds by the score.
Updated: March 18, 2021
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How to Grow Butterfly Bush
The popularity of butterfly bushes is no surprise as they're beautiful, easy to grow, and require minimal day-to-day care. Even major storms have little effect on these hardy shrubs. They thrive in harsh environments, such as polluted urban settings. They're also resistant to insects, drought, and stress. The bushes require little attention, so even weekend gardeners can enjoy their lovely blooms and resident butterflies.
Butterfly bush is very easy to grow in average, medium moisture, well-drained soil in a full sun location. If planting more then one, space them well apart—five to six feet. Blend in peat moss before planting if the soil is dense and poorly draining.
In colder climates, butterfly bush often dies back to the ground in winter and is treated like a herbaceous perennial. And in warm climates, they can be pruned back in the same way to keep them under control and stimulate better blooming. Be wary of this plant's tendency to aggressively spread through self-seeding. Removing the spent flower clusters before they can scatter seeds will help control the plant.
There are no serious pest or disease problems with butterfly bush, although spider mites can be an issue, and nematodes can be a problem in the South.
Butterfly bush is a deciduous to semi-evergreen perennial that is hardy enough to survive winter in USDA zone 5. It flowers all summer and into the fall, usually from June through October, provided the spent flowers are deadheaded regularly. Flowering peaks in July and August. This fast-growing shrub may reach its mature size within one or two seasons after planting. At maturity, the shrubs may reach 6 to 10 feet tall and 4 to 10 feet wide.
The flower clusters, called panicles, are 5 to 12 inches long. Flower colors include blue, yellow, white, pink, purple and lavender, and they are pleasingly fragrant. Butterfly bush is a staple for wildlife habitats and when you want to attract pollinators. The flowers provide a rich source of nectar for bees, butterflies, lady beetles and hummingbirds.
Creating Attractive Borders
The dwarf, mounding behavior of these butterfly bushes make them ideal for use in borders. Their colorful flowers mixed with their pointy green and sometimes variegated leaves add texture and interest to the front of your flowerbeds while your larger shrubs and taller perennials can stand out in the back. When using them as a border, you can plant them 2 to 3 feet on center to make a very short hedgerow. You can also space them further apart for a different look.
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Who can resist the allure of a plant named butterfly bush? Just mentioning this name gives us a good feeling. The image that immediately comes to mind is Monarchs, Swallowtails, and other butterflies flitting to and fro about this brightly colored plant in the warm sunshine. Another image is one of brightly colored flowers, pleasing to the eye, while many other plants struggle to flower during the hottest part of the summer.
Butterfly bush, or Buddleia, has long been a garden favorite. Like many favorite garden plants, this group of summer flowering shrubs recently received an industry makeover. The result is a plant gardeners should consider, deserving of a place in the landscape or flower garden.
Buddleia is a resilient plant. It is right at home in our Kansas City gardens being hardy from zone 5 to 9. Butterfly bush occasionally has problems with winterkill, resulting in sporadic dieback in the canopy. This is not a problem. In fact, it might be a big help for those gardeners uneasy about pruning shrubs. Although the plant is tolerant of winter conditions, it sometimes struggles to survive during a wet, cold winter. The roots are susceptible to root rot, which leads to the plant dying. Even though butterfly bush is a perennial shrub, it can fail under these winter conditions.
Butterfly bush is a summer flowering shrub blooming best when located in full sun. It will tolerate part-sun and bloom just fine, but the increasing shade will reduce flowering. If it does not thrive, try relocating it into more sunshine. Keep in mind the butterflies prized for necturing on this plant prefer the warm sun.
Watering needs are minimal as the plant is drought tolerant. With that being said, like any plant, it will flower and thrive best with a steady supply of moisture.
Proper pruning of this plant is a must for best flowering. Fortunately, it is a simple process. Butterfly bush flowers on new growth, meaning the shoots that develop during the growing season produce all the flowers. The recommended style of pruning for this is referred to as rejuvenation. Basically, that means the plant is cut back hard each spring just before growth begins. Remove all limbs or branches back to a height of about 1 foot. If you are a hedge trimming kind of pruner, this is the plant for you. The only way you can fail at pruning this plant is by either not pruning it at all, or not cutting it back enough. Once the upper stems are removed, cut or break off all the dead stems back to the ground to clean up the base of the plant.
The beauty of this plant is the fact that it will flower for an extended period compared to other shrubs. Flowering begins in June and will continue blooming until the first frost in September or October.
Deadheading is the removal of the old flower clusters. Some people wonder if this plant needs deadheading. My answer is it depends on your style. Remove the faded flowers for the best flower production. The more the plant is deadheaded, the bigger the reward. Just snip off the blooms below the long arching flower stalk to encourage new growth and flowering. It helps keeps the plant cleaner and more beautiful.
If you have grown this plant, you know they can get quite large. The old standard favorite varieties may reach a height of 5 feet or more by the end of summer. They bloom in a variety of colors, including shades of blue, purple, pink, white, and even some bicolor blossoms. There is also a variety of flowers in yellow. The flower clusters are long arching stalks containing many tubular shaped blossoms. This shape makes it easy for the butterflies and hummingbirds to feed, with their long proboscis or beak quickly reaching the sweet nectar.
Such old-time favorites varieties include Black Night,’ dark purple ‘Nanho Blue,’ mauve-purple ‘Nanho Purple,’ magenta-purple ‘Pink Delight,’ true pink ‘Royal Red,’ purple-red and ‘White Profusion,’ a pure white, to name a few.
Recent varieties are now compact and sterile. This small, rounded habit helps make the plant even more versatile in the landscape. The dwarf varieties range in height from about 2 to 3 feet. As a result, they work great planted en masse along walks in the front landscape or dotted throughout the traditional perennial garden. These newer dwarf varieties tend to have all the great strengths of their older parent but on a smaller scale. Expect the same heat tolerances, water needs and sun patterns.
One of the first dwarf varieties on the market was Lo & Behold ® ‘Blue Chip’. Our Extension Master Gardeners added it to their demonstration garden years ago. The continuous blooms come in a delightful shade of blue. The panicles are 4 to 6 inches and create an excellent rounded form. Lo & Behold ® ‘Purple Haze’ has also been a winner in our demonstration garden, with the same habit as the blue form, but in a delightful light-purple flower color.
There is a series of dwarf butterfly bushes on the market called Flutterby Petite. The breeders have done a superb job of developing a range of colors. These include ‘Blue Heaven,’ ‘Snow White,’ ‘Tutti Fruitti Pink,’ ‘Dark Pink’ and ‘Pink. Pugster is the newest variety promoted as the plant with the largest flower clusters.
Butterfly bush has long been a staple in the Kansas City garden for a good reason. But now, with these newer releases, there are even more reasons to include this plant in the garden. As you make your summer planting plans, be sure to include a few butterfly bushes. You will enjoy the summer color while watching the butterflies and hummingbirds also enjoying the garden for years to come.
Have questions? The Garden Hotline is staffed by trained EMG volunteers and Extension staff who will assist you with questions.
Buddleja fallowiana: This is one of the best butterfly bushes for foliage interest. The leaves are 2 to 4 inches long and heavily felted, giving a decidedly silver-gray overall appearance. Plants can reach 10 to 15 feet tall, but can easily be maintained lower. Flower heads are white to lavender and 6 to 8 inches long. ‘Alba’, the most commonly seen cultivar, is more compact than the species, with white flowers.
Sageleaf Butterfly Bush (Buddleja salviifolia): This species is grown primarily for its foliage. It has highly textured leaves that are coppery-green. Flowers are a pale lavender and not especially showy. It is a large shrub (15 to 20 feet tall) from South Africa. It flowers on the previous year’s wood and should be pruned after flowering. It is very hardy and may remain evergreen in Zones 7-9.
Alternate-leaf Butterfly Bush (Buddleja alternifolia): This species is a deciduous shrub with alternate leaves unlike other Buddlejas. It is a very hardy, rapid growing, tall plant (13 to 15 feet) with a weeping habit. This butterfly bush produces purple flowers early in the season on the previous year’s wood and should be pruned after flowering.
Lindley’s Butterfly Bush (Buddleja Lindleyana): This butterfly bush has small dark green leaves and lavender-purple flowers. It is a smaller shrub (4-5 feet) with gracefully arching branches and fragrant panicles. This species will spread by suckers to colonize large areas.
If this document didn’t answer your questions, please contact HGIC at [email protected] or 1-888-656-9988.
Cory Tanner, Horticulture Extension Agent, Greenville County, Clemson University
This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.