Aconitum, also known as aconite, monkshood, wolfsbane, leopard’s bane, devil’s helmet, or blue rocket, is a genus of over 250 species of flowering plants belonging to the family Ranunculaceae. The name “aconitum” is derived from the Greek word “akon,” which means dart or javelin, possibly referring to the plant’s historical use as a poison on weapons. The name “monkshood” comes from the flower’s resemblance to a monk’s cowl.
Aconitum species are native to the mountainous regions of the Northern Hemisphere, including North America, Europe, and Asia. Historically, the plant has been associated with both ornamental and medicinal uses, though it is infamous for its toxic properties.
Monkshood is a tall, herbaceous perennial plant that can grow up to 2-5 feet tall. It features dark green, palmate leaves with deep lobes and racemes of large, zygomorphic flowers1. The flowers come in shades of blue, purple, white, yellow, or pink and have a distinctive hood-like shape due to the curved top sepal.
Interesting varieties of monkshood include Aconitum septentrionale “Ivorine,” with flowers of creamy white, and Aconitum cammarum “Bicolor,” with blooms streaked with white and blue. One of the tallest cultivars, the amethyst blue-flowered Aconitum henryi “Spark’s Variety,” reaches over 5 feet tall if staked, but otherwise tends to vine and can even be trained to a trellis.
Depending on the variety, monkshood blooms any time between mid-summer and late summer with magnificent 2- to 5-foot-tall spires of deep purple or blue helmet-shaped flowers.
Characteristics
- The flowers are the most common feature, forming hood-like structures (hence the name “Monkshood”), with the upper sepal forming a hood over the rest of the flower, which can be blue, purple, white, yellow, or pink. The bloom time falls in late summer to early fall.
- Leaves are deeply lobed or palmately divided, resembling those of a maple or geranium, providing an interesting backdrop to the flowers.
- Aconitum plants are perennials, growing from tuberous roots. They can vary in height from 1 to 4 feet or more, depending on the species and variety, with upright, often unbranched stems.
- All parts of the plant are highly toxic if ingested, containing alkaloids like aconitine, which can affect the heart and nervous system. Handling should be done with care, and wearing gloves is recommended.
- Aconitum thrives in moist, well-drained soils and is often found in mountainous regions, woodlands, and alpine meadows.
- In U.S. Department of Agriculture plant hardiness zones 3 through 8, these plants die back in the winter. Monkshood plants establish slowly, so the best time to plant them is in the spring.
Cultivation
Soil: Monkshood prefers moist, well-drained, humus-rich soil. It does well in loamy soils but can adapt to various soil types as long as they are not waterlogged or too dry.
Planting: Best planted in spring or early autumn. Plant tubers about 2 inches deep. Space plants about 12-18 inches apart to allow for growth and air circulation.
Watering: Requires consistent moisture, especially during the growing season. Mulching around the base can help retain moisture and keep roots cool. However, ensure the soil isn’t waterlogged to prevent root rot.
Light: Prefers partial shade to full sun, but in hotter climates, some afternoon shade is beneficial. Too much sun can cause the leaves to wilt, especially if the soil isn’t kept moist.
Temperature: Monkshood thrives in cooler conditions, making it suitable for temperate climates. It can tolerate cold winters, being hardy in USDA zones 3-7, but might need protection in zones where temperatures drop severely.
Fertilization: A light application of a balanced fertilizer in early spring can promote vigorous growth. Compost or well-rotted manure added in the fall or early spring also benefits the plant.
Pests and Diseases: Generally resistant to most pests and diseases due to its toxic nature, but watch for aphids, slugs, and snails. Powdery mildew can occur in overly wet conditions or if air circulation is poor.
Propagation: Best propagated by dividing the tuberous roots in early spring before new growth starts. Can also be grown from seed, though it takes longer to bloom. Seeds should be sown in fall for natural stratification.
How to Get a Monkshood Plant to Re-Bloom
- Put on gardening gloves before working with monkshood, because all parts of this plant, including the roots, are poisonous. If you accidentally expose your skin around this plant, wash with soap and water immediately.
- Use pruning shears to cut back the stems to lateral buds after the first flush of bloom is finished. This will encourage a second round of blooms in the same season.
- Deadhead all spent flowers from the second flush of bloom in the fall, using the same method as Step 2. If the remaining foliage looks tatty or pale, cut the plant down to its basal growth. It’s possible that even the basal growth will produce some flowers.
- Fertilize the plant with a general-purpose fertilizer following its last bloom of the season. Allow the basal growth to remain over the winter.
- Trim off any dead or unsightly foliage early in the spring. Fertilize the plant with a general-purpose fertilizer.