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.