How to Grow Monkshood

Monk's hood flowers

The Spruce / Autumn Wood

Native to mountainous areas in Europe and Asia, monkshood is a tall herbaceous perennial flower that blooms late in the summer and handles partial shade very well. It gets its common name from its resemblance to the cowl on monk’s habits. There are about 250 species of aconite, but Aconitum napellus is the most commonly grown ornamental variety.

A moderately slow-growing flower, monkshood features smooth palmate leaves with deep lobes and racemes of blue or white flowers on sturdy, unbranched stems. Planted in early spring, the flowers on monkshood begin to emerge in mid-summer and feature five sepals—the top sepal curves downward, giving the flower its hood-like appearance, while the actual petals are hidden inside the hood.

Though monkshood has been safely cultivated in gardens for hundreds of years, it is known to be extremely poisonous. You’ll find many references in literature to monkshood being used to kill enemies (fed as poison or used in arrows), and yet another common name for monkshood, wolf's-bane, refers to its use for getting rid of wolves.

Botanical Name Aconitum napellus
Common Name  Monkshood, wolf's-bane, devil's helmet
Plant Type  Herbaceous perennial
Mature Size  2–4 ft. tall, 1–2 ft. wide 
Sun Exposure  Full sun, partial shade
Soil Type  Moist but well-drained
Soil pH  Neutral to acidic
Bloom Time  Summer
Flower Color  Blue, purple
Hardiness Zones  3–7 (USDA) 
Native Area  Europe, Asia
Toxicity  Toxic to dogs, cats, and humans
Monk's hood flower
​The Spruce / Autumn Wood 
monk's hood flowers
Josie Elias / Getty Images

    Monkshood Care

    Commonly beloved for its beautiful, true-blue color, monkshood flowers can mostly be found in the mountains of the Northeastern United States. The blooms are able to thrive in various types of soil, so long as they receive lots of water and sunshine. Since these are late-season bloomers and they do not repeat bloom, you won’t really need to deadhead—the plants will die back to the ground at frost.

    Though a beautiful flower—and therefore desirable to professional and novice gardeners alike–great care should be taken before choosing to plant monkshood in your garden. If you have curious children or nosey pets around, this is one varietal you're better off skipping.

    Light

    Monkshood can handle both full sun and partial shade. Typically, the sunnier the spot, the better for the bloom—however, if you live in an especially warm area, you're better off opting for a partially-shaded spot so you don't burn the delicate petals. If you notice the heads or stems of the flower drooping, it is probably receiving too much shade. If moving your plant isn't an option (like in the case of a pot or container garden), use stakes to keep them upright.

    Soil

    Monkshood thrives best in a moist environment. Typically, that means a rich soil mixture—however, in the case of monkshood, that can mean a dense organic blend or a rocky, mountainous one. The only requirement: The chosen spot needs to be well-draining to prevent root rot. The plant prefers a soil pH that is neutral to slightly acidic but will tolerate other soils as long as they meet the above criteria.

    Water

    A thirsty drinker, monkshood likes to be kept consistently moist but not waterlogged. Frequent watering is important during its growth period (spring) and, once established, monkshood is able to withstand short periods of drought. However, if it's a robust and lush flowering plant you desire, provide consistently moist soil and water regularly throughout its lifespan.

    Temperature and Humidity

    The monkshood flower prefers cooler weather, thriving in mountainous landscapes that don't boast much humidity or high temperatures. Keep in mind, the warmer the weather, the more shade the plant will need.

    Fertilizer

    Feeding always depends on the quality of your soil. Start with rich soil, high in organic matter, then side-dress with compost and some organic fertilizer each spring.

    Is Monkshood Toxic?

    Unfortunately, monkshood is as toxic as it is beautiful. The plant is extremely dangerous to both animals and humans. Though the seeds and roots of the plant are the most toxic, all parts of monkshood are poisonous if ingested, or if the sap comes into contact with any mucous membrane. Always use gloves wash your hands after handling monkshood, and do not grow the plant around children or pets. If you experience any of the symptoms of poisoning, contract 911 or poison control immediately.

    Symptoms of Poisoning in Animals

    • Abdominal pain
    • Frothing at the mouth
    • Abnormal heart rate
    • Numb limbs
    • Paralysis
    • Pawing at mouth
    • Seizures
    • Trouble breathing
    • Vomiting
    • Weakness or lethargy

    Symptoms of Poisoning in Humans

    • Nausea or vomiting
    • Burning or tingling
    • Paralysis or numbness
    • Dizziness
    • Headache
    • Sweating, or burning/cold sensation
    • Confusion
    • Slow pulse
    • Trouble breathing
    • Foaming at the mouth

    Monkshood Varieties

    Many gardeners are partial to common monkshood because of its intense, rich blue color and easy growing nature. However, there are also a handful of worthy cultivars and species, including:

    • Aconitum septentrionale "ivorine": An early blooming varietal of monshood featuring elongated, white flowers
    • "Albus": The familiar monkshood with, as the name implies, white flowers
    • "Blue sceptre": A unique multi-colored version of monkshood, featuring white and blue flowers
    • Aconitum hendyi "spark's variety": A monkshood varietal with branched flower stalks, giving it a fuller appearance

    How to Grow Monkshood From Seed

    Like many flowers, you can start monkshood from seed—however, it can be finicky about germination and may take a year or more to sprout. Because of this, it's a good idea to "start" extra seeds, with the expectation that some of them won't end up germinating.

    Sow the seed in late fall for germination in the spring—they need to go through a chilling period in winter to break dormancy. The plants don’t really like to be transplanted, so direct sow instead of starting in containers indoors first if possible. They can be ephemeral their first year, so don’t panic if they disappear.