Butterbur, or Petasites hybridus, is a spreading shrub long-cherished for its impressive leafy displays and traditional medicinal applications. Also known as butterfly dock and pestilence wort, Europeans brought the plant to North America as an herbal treatment for ailments ranging from migraines to fever and asthma.
Always consult your physician before using herbal remedies at home, but don't hesitate to grow butterbur as a feature in your garden. From their striking blooms to their saucer-like leaves, butterbur is an attractive addition to any garden.
Butterbur works beautifully as a ground cover or in wet landscapes. It spreads quickly via rhizomes, underground stems that grow horizontally, pushing new shoots up through the dirt as they go. If you plan on cultivating butterbur in your garden, be sure the plant has enough room to spread out, such as in a large garden or wet meadow. If you aren't careful, the plant will become invasive.
Usually found along streams and riverbanks, butterbur prefers moist, nutrient-rich soil. Plant your butterbur in a wet or easily-watered section of your garden, preferably in sandy, loamy, or clay soil. You also want to keep those rhizomes under control to prevent them from becoming invasive.
Keep the plant in the space you want by first lining the planting hole with a pond liner or rhizome barrier. If you choose an outdoor pot, make sure there aren't any drainage holes through which rhizomes can escape.
Butterbur prefers lightly shaded or partially shaded garden beds with some dappled sunlight. It will also thrive in full shade, which is good news if you're planning for a shade garden. Be sure to check your specific butterbur plant's needs, as some varieties prefer more sunlight than others.
Full sun can suck away the much-needed moisture from the soil and scorch the leaves, especially in the summer.
It's probably become clear already, butterbur love water and high humidity. Moist patches of soil or areas with slow water drainage make the ideal habitat. Keep the plant's soil evenly moist, watering when the dirt is dry one to two inches beneath the surface.
Butterbur doesn't thrive in dry conditions, so you may want to flood the garden bed during the summer months and heatwaves to keep the foliage from wilting.
Butterbur prefers nutrient-rich soils, so mixing compost with your substrate before transplanting provides a good foundation. Keep your shrub vibrant and robust by adding fertilizer during spring and once a month during the summer.
Make sure your fertilizer has a ratio of 16-4-8; that denotes the concentration of nitrogen, phosphorus, and potassium, respectively.
Petasites hybridus thrives in USDA Plant Hardiness Zones four to nine, which accounts for most of the U.S. from the Northeast to the Southwest. Plant hardiness zones refer to the average annual minimum winter temperature in a region. Zone 4 reaches an average low of -25 degrees Fahrenheit — which means that butterbur is pretty darn hardy.
Your new butterbur plant loves to spread out, so pruning is essential to keep its growth under control. In autumn, use the edge of a spade to thin out the foliage. First, cut the rhizomes through the dirt with a shovel, then dig out the unwanted segments, removing them from the soil.
While this seems like a lot of work, the good news is that butterbur's broad foliage prevents weeds — or anything else, for that matter — from growing around its base.
Butterbur's hardiness to -25 degrees Fahrenheit means that you don't have to do much to keep them over the winter. That doesn't mean your plant isn't thirsty, however. Remember to keep the soil evenly moist, especially if the humidity levels are lower than ideal. You should also make sure your plants have shelter from strong winds, which can tear and damage the foliage.
Propagate your Petasites hybridus by digging up rhizomes and dividing them into smaller pieces. Transfer the rootstalk to a pot and gift the plant to a friend, or sow it in another garden to cover more ground. For best results, transplant the rhizomes when there is no danger of frost — preferably in the early spring.
In addition to being cold-weather hardy, butterbur is resilient to disease. That doesn't mean an infection isn't possible, however. Your plants can become infected with the butterbur mosaic virus, which creates a discoloration on the leaves, or the tomato spotted wilt virus. Both of these diseases circulate via insect infestation.
Your best bet to preventing illness is by keeping pests like aphids and thrips away and discarding infected rhizomes rather than using them to propagate new plants.
Butterbur plants don't typically show signs of infection, but they have fallen victim to slugs and snails. These pests love young butterbur leaves, so keep an eye out for them during the early summer when new foliage buds. Remove the slimy trespassers by hand, or use snail and slug repellents or traps.
Search online for preventative solutions and natural deterrents if you're looking for a more humane solution.
The draw of growing Petasites hybridus is its impressive spread: tall stalks of purple-rose flowers, broad, heart-shaped leaves, and their towering stature — up to three feet tall. Use it alongside streams or at the edge of a pond or natural pool to create an attractive screen.
Cover lots of ground, or use it in a group planting with similar moisture-loving plants. Use butterbur to fill large planters or add greenery to water gardens.
Butterbur is part of the Asteraceae plant family — which includes daisies and sunflowers. It is also related to dandelions and marigolds, though butterbur resembles its cousin, the artichoke, more closely.
One distinct attribute, however, is the perennial Petasites' flowers. They bloom very early in the year before the leaves begin to develop. It isn't until the flowers die off that the massive leaves steal the show. This unique attribute makes butterbur a fascinating choice for your garden.
The leaves of the butterbur shrub are so large that they shade out surrounding vegetation, leaving bare earth at the base of the plant. That might work for keeping weeds out of the garden, but not so much for other plants you want to flourish alongside. Keep this in mind while planning your garden bed layout.
While a lot of anecdotal evidence supports butterbur for treating ailments like migraines or inflammation, we now know that the plant contains liver-damaging toxins. Consult your doctor before adding butterbur as an herbal supplement.
There aren't any varieties of the Petasites hybridus, but the Petasites japonicus is a closely related species. Originating from Japan, japonicus' appeal is its stunning display of pale flowers and variegated foliage. Mature plants fill garden beds with splashes of creamy white on brilliant green leaves for a touch of drama.
The winter heliotrope, Petasites fragrans, is a winter-flowering plant with a lovely vanilla fragrance, though it isn't as hardy as butterbur.