The Jack-in-the-Pulpit (Arisaema triphyllum) is a unique plant for shade gardens. Its common name describes its distinctive appearance: a hooded, vase-like spathe (“pulpit”) enclosing a central club-like spadix (“Jack”). This structure makes it a focal point in woodland settings. Bright red berries appear in late summer, adding visual interest.
Site Selection and Planting
Choosing the optimal location for Jack-in-the-Pulpit is important for establishment. These plants thrive in woodland habitats, preferring partial to full shade. Avoid direct, intense sunlight, which can scorch foliage.
Prepare the soil by incorporating organic matter like compost or well-rotted leaf mold. This provides nutrients and improves moisture retention. Good drainage prevents corm rot, though the plant tolerates moist conditions.
When planting, place corms six inches deep with pointy ends upwards. Fall or early spring are suitable times for bare-root corms, allowing stronger root establishment. For seedlings or divided corms, space them six to twelve inches apart. After planting, water thoroughly to settle soil and ensure consistent moisture.
Ongoing Care
Once established, Jack-in-the-Pulpit plants require consistent conditions to thrive. Providing the right balance of light, soil, water, and minimal fertilization contributes to their vigor. Mimicking their natural woodland habitat is key.
Light
Jack-in-the-Pulpit performs best in partial to full shade. In its natural environment, it is found beneath forest canopies, receiving dappled sunlight. While it tolerates deep shade, a few hours of indirect light or morning sun can support robust growth. Avoid direct afternoon sun to prevent leaf scorch.
Soil
Ideal soil for Jack-in-the-Pulpit is rich in organic matter, moist, and well-draining. A slightly acidic to neutral pH (5.5 to 7.5) is preferred. Amending with compost or leaf mold improves fertility and creates a humus-rich environment. Good drainage prevents waterlogging, which can harm corms.
Water
Consistent soil moisture is important for Jack-in-the-Pulpit during active growth. The plant should not dry out. Watering weekly is a general guideline to maintain dampness. It tolerates wet soils, making it suitable for rain gardens or boggy areas.
Fertilization
Jack-in-the-Pulpit does not require heavy fertilization if planted in rich, organically amended soil. A yearly top-dressing of compost in spring provides sufficient nutrients and maintains soil fertility. If soil nutrients are lacking, a balanced, slow-release granular fertilizer (e.g., 10-10-10) can be applied sparingly. Avoid high nitrogen fertilizers.
Understanding the Lifecycle and Dormancy
The Jack-in-the-Pulpit exhibits an annual lifecycle: spring emergence and subsequent dormancy. In early spring, the plant sprouts from an underground corm, sending up its distinctive spathe and spadix, often followed by one to two trifoliate leaves. The hooded flower structure (green, purplish-brown, or striped) is visible from April to May.
By mid-to-late summer, the plant enters dormancy. Leaves and floral structures yellow and wither, disappearing from the garden. This process allows the plant to conserve energy in its underground corm. If pollination was successful, bright red berries may remain visible on a stalk, adding color after foliage recedes. The plant re-emerges the following spring from its corm, continuing its cycle.
Propagation
Propagating Jack-in-the-Pulpit can be achieved through seed collection and corm division. For seed propagation, collect bright red berries in late summer or early fall when ripe. Each berry typically contains one to five seeds. Clean seeds by removing the surrounding pulp, which contains germination inhibitors, then rinse.
Jack-in-the-Pulpit seeds require cold stratification (60 to 90 days) to break dormancy. Mix cleaned seeds with damp sphagnum peat moss and refrigerate. After stratification, sow seeds on the surface of a moist, well-draining potting mix, as they need light to germinate, and keep them consistently moist. Germination can take weeks; seedlings often need to grow indoors for up to two years before transplanting outside.
Corm division is a quicker propagation method. This is best done in late fall after dormancy or early spring before new growth. Dig up the root clump, consisting of a main corm and smaller offsets (cormlets). Gently break off these corm offsets, ensuring each piece has a growth point. Replant the parent corm and separated offsets immediately at the same depth in a suitable shaded location with rich, moist soil.
Common Problems and Toxicity
Jack-in-the-Pulpit is generally robust, rarely affected by pests or diseases. Slugs can be an issue, managed through hand-picking, traps, or slug baits. Good air circulation and cultural conditions help prevent fungal issues.
Despite its beauty, all parts of the Jack-in-the-Pulpit (leaves, stems, corms, berries) contain calcium oxalate crystals. These crystals cause pain, irritation, and swelling if ingested or if sap contacts sensitive skin. Wear gloves when handling, especially during propagation or if damaged. Exercise caution around children and pets to prevent accidental ingestion. While birds and some animals may eat ripe berries, deer and rabbits generally avoid the plant due to its toxicity.