How to Grow and Care for Jack in the Pulpit
Cultivate the native Jack in the Pulpit by understanding its complete lifecycle and replicating its natural woodland environment for long-term success.
Jack in the Pulpit (Arisaema triphyllum) is a perennial native to the woodlands of eastern North America. Its name comes from its unique spring flower, which consists of a central, club-like spadix (“Jack”) enveloped by a hooded, leaf-like spathe (“pulpit”). The spathe is often green or purplish and can be marked with stripes of green, white, or purple.
Above the flower are one or two large, glossy leaves, each divided into three leaflets. The plant emerges from an underground corm, a swollen, bulb-like stem that stores food. This appearance gives it a tropical feel, making it a popular specimen for shade gardens. The flower’s structure also plays a role in pollination by attracting small flies and gnats.
Planting and Growing Conditions
To successfully grow Jack in the Pulpit, replicate its native woodland habitat. The plant thrives in partial to full shade, such as under the canopy of deciduous trees. Avoid direct sunlight, which can scorch the foliage and inhibit growth or prevent mature plants from blooming.
The ideal soil is rich in organic matter, consistently moist, and well-draining with a slightly acidic to neutral pH between 6.0 and 7.0. Amend heavy clay soils with compost or leaf mold to improve fertility and structure. The soil should remain evenly moist during its active growing period in spring and early summer, but avoid waterlogged conditions which can lead to root rot.
These plants are hardy in USDA zones 4 through 9. Plant corms in the fall about six inches deep with their pointed ends facing up, or set out nursery-potted plants in the spring. Space individual plants 6 to 12 inches apart to allow for growth. In rich soil, heavy feeding is not required, but a balanced, slow-release fertilizer can be applied in early spring as new growth emerges.
Seasonal Care and Lifecycle
In spring, the plant emerges from its corm, sending up leaves and its flower structure. The flowers appear from April to May, which is the plant’s most active period for drawing energy from the soil.
As summer approaches, the plant’s cycle changes. After flowering, the leaves and spathe may begin to yellow and wither as the plant enters dormancy. For mature female plants that were successfully pollinated, the focus shifts to developing a dense cluster of berries. These berries start green and ripen to a bright red in late summer, becoming more visible as the spathe dies back.
The plant remains dormant underground through fall and winter. The red berry cluster can be left on the stalk for visual interest and as a food source for wildlife. After the ground freezes, apply a thick layer of mulch, like shredded leaves, to protect the corm from harsh temperatures.
Common Problems and Solutions
Jack in the Pulpit is a low-maintenance plant with few insect or disease problems. The moist, shady conditions it prefers can attract slugs and snails, which damage the leaves. They can be managed by placing a small dish of beer near the plants as a trap.
Diseases are uncommon, but rust can occasionally affect the leaves. Root rot is a concern in poorly drained soil, so ensuring proper drainage is the best prevention.
A Jack in the Pulpit may fail to flower for a few reasons. It can be due to the plant’s age, as it can take up to five years for one grown from seed to reach maturity. For mature plants, a lack of flowers might indicate insufficient light in dense shade or soil that is not fertile enough. Ensuring the plant has access to dappled sunlight and rich soil can encourage flowering.
Toxicity and Handling
All parts of the Jack in the Pulpit plant are toxic to humans and pets if ingested. The plant contains microscopic, needle-shaped calcium oxalate crystals. If chewed or swallowed, these crystals embed in the mouth and throat, causing immediate pain, irritation, swelling, and drooling.
Wear gloves when handling any part of the plant, as its sap can cause skin irritation. The calcium oxalate crystals also serve as a defense mechanism, deterring deer and other animals from eating the foliage.
Plant Jack in the Pulpit away from areas frequented by children and pets. While ingestion is rare due to the immediate pain, this is a sensible precaution for a family garden.