Common butterbur (Petasites hybridus) is a robust perennial with an erect, spreading growth habit. The plant flowers in the early spring, though it’s primarily grown for its lush foliage. The tiny flowers bloom in clusters atop tall, thick flower stalks. The large medium green leaves are heart-shaped, and the biggest among them can stretch more than a foot across. They are smooth on their top and somewhat wooly on their underside. There are even variegated varieties that have cream and green leaves. Common butterbur has a fast growth rate and is best planted in the spring after the threat of frost has passed.
|Botanical Name||Petasites hybridus|
|Common Names||Common butterbur, butterbur, bog rhubarb, pestilence wort, devil’s hat|
|Plant Type||Herbaceous, perennial|
|Mature Size||Around 3 ft. tall, 5 ft. wide|
|Sun Exposure||Partial, shade|
|Soil Type||Loamy, clay, moist|
|Soil pH||Acidic, neutral|
|Hardiness Zones||4–8 (USDA)|
|Native Area||Europe, Asia|
|Toxicity||Toxic to people and animals|
Common Butterbur Care
Common butterbur grows naturally in shady, moist soil near rivers and in meadows. Thus, it’s a good choice for woodland and rain gardens, as well as around the perimeter of water features. However, the biggest challenge in growing butterbur plants is keeping them from spreading to where you don’t want them. Propelled by vigorous rhizomes (underground stems), they are invasive plants whose natural tendency is to colonize. Thus, growing them in containers or within garden barriers can be helpful if you don't want to have to spend a lot of time removing unwanted plants.
Other than containing their spread, caring for these plants is relatively easy. Just be sure they are getting sufficient water, and fertilize annually if you don’t already have rich soil. Common butterbur plants generally don’t have any major problems with pests or diseases, though slugs eating holes in the leaves sometimes can be an issue. Slugs can be controlled through both chemical pesticides and natural solutions. Likewise, strong winds can damage the leaves, so aim to situate your plants in a somewhat sheltered location.
Shady conditions are ideal for common butterbur plants, though they also can grow in partial sun. In fact, the variegated varieties tend to achieve the best foliage coloration in partial sun. However, too much sunlight can cause the leaves to wilt and/or burn. If this occurs and you are able to relocate your plant to a shadier spot, the damaged leaves eventually will fall off and be replaced with fresh foliage.
Common butterbur isn’t overly picky about its soil type. It can grow in sandy soil as long as it gets enough water. But a loamy or clay soil that retains more water is best. A slightly acidic to neutral soil pH is ideal.
These plants thrive in evenly moist soil, and they can handle occasional flooding. Water whenever the soil begins to dry out about an inch or two down. And in hot weather, be sure to give the plants a little extra water.
Temperature and Humidity
Common butterbur tolerates the hot and cold temperatures of its growing zones well, as long as it has the right amount of water, shade, and wind protection. It prefers moderate to high humidity levels and will likely need more frequent watering in dry climates.
An organically rich soil is ideal for common butterbur. At the time of planting, mix some compost into the soil to enrich it. If you already have fertile soil, you might just need to keep adding a layer of compost in the spring to ensure healthy growth. To further boost common butterbur's growth, use a fertilizer with a ratio of 16-4-8 for nitrogen, phosphorus, and potassium, following label instructions.
Is Common Butterbur Toxic?
Although some people use butterbur as an herbal remedy for migraines, allergies, and other conditions, all parts of the butterbur plant contain pyrrolizidine alkaloids, which can be harmful to both people and animals when ingested.
Symptoms of Poisoning
Side effects in people and animals from ingesting butterbur include upset stomach, diarrhea, headache, and fatigue. It also might bring on allergic reactions, especially in those who are also sensitive to plants such as ragweed and daisies. Moreover, the pyrrolizidine alkaloids can be harmful because they are known to damage the liver, though issues would likely arise from long periods of ingesting butterbur and not one isolated event. If you suspect poisoning, contact a medical professional as soon as possible.
There are several species and varieties of butterbur that slightly differ in appearance, including:
- Petasites japonicus: Commonly known as butterbur or fuki, this species is similar in size to common butterbur and also has large leaves. Its blooms are yellowish-white.
- Petasites albus: Also known as white butterbur, this plant features clusters of white blooms in the spring.
- Petasites pyrenaicus (or Petasites fragrans): Also referred to as winter heliotrope, this species sports mauve-pink flowers that have a light vanilla scent.