Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
What are Jack in the Pulpit?
Jack in the Pulpit (Arisaema triphyllum) is a perennial plant that is native to the Eastern North American woodlands. It is related to another Eastern North American native, the skunk cabbage. They look nothing alike, except for their flowers which both consist of a spadix covered by a spathe.
Jack in the Pulpit grows in shady, damp areas. It loves wet boggy soil and can frequently be found along the banks of streams. It is hardy in zones 4 – 9. The plant grows 1 to 2 feet tall from a corm. The larger the plant, the larger and older the corm.
In the spring when the leaves appear, they are often mistaken for poison ivy because they grow in groups of three leaflets like poison ivy.
The flowers appear in April through June depending on the species. Their distinctive shape give the plant its name. The spadix which contains the male and female flowers is the “Jack” in Jack in the Pulpit. The spathe which arches over the spadix is the “pulpit” from which “Jack” preaches. The spathe is usually green, but in some species the spathe is striped green and maroon.
To avoid self-pollination, the male flowers open before the female flowers. Consequently, the female flowers have to be pollinated by male flowers from other plants. Interestingly, younger plants have more male flowers than female flowers. They are considered “male” plants. Older plants have more female flowers than male flowers and are considered “female” plants. The male plants have a hole at the bottom of the spathe so that pollinating insects can escape to fly off to female plants to fertilize them. The female plants don’t have a hole at the bottom of the spathe making it more difficult for pollinating insects to escape creating a better opportunity for the female flowers to be fertilized.
After the flowers die, they are replaced by berries. The berries start out green, then turn orange in late summer, August through early September, finally ripening to red in the fall. Each berry contains 1 to 5 white to tan seeds.
How to Grow Jack in the Pulpit
To successfully grow Jack in the Pulpit you must imitate its native forest environment: wet acidic soil that is rich in organic matter. If you are not creating a woodland garden, a good spot in your yard would be a shady area that stays damp most of the time. In that case you should enrich the soil by working in compost and leaf mold. Add compost and leaf mold or just leaf mold every year. No other fertilizer is required. If there is a prolonged period with no rain, be sure to keep that area well watered. A thick layer of mulch will help keep the soil moist.
Jack in the Pulpit grows from corms. That is what you will receive if you are ordering from a catalog or an online site. The corms are planted in the fall at the same time as your tulips and daffodils. Plant your corms, root side down, in holes that are 6 inches deep and 6 to 12 inches apart.
Jack in the Pulpit are not bothered by pests or disease except for slugs. A ring of crushed eggshells around your plants will kill any slugs that try to get near your plants. Since I put my eggshells in my composter, I use beer traps. Beer traps are bowls filled with beer that you sink into the ground so that slugs can get in. They are attracted by the smell of the beer, climb into the bowls and drown.
How to Grow Jack in the Pulpit From Seed
If you want to grow Jack in the Pulpit from seed, you will need fresh seed. Harvest some berries when they are mature. Gently roll them in your fingers until the seeds come out.
You can direct sow the seeds in your garden in the fall when you harvest them from the berries. Plant the seeds ½ inch deep and 6 to 12 inches apart. Keep them watered until the ground freezes. They will be fine over the winter. They need that period of cold in order to germinate. In the spring, don’t be disappointed if all you see is a single leaf from each seed. It will take up to 3 years for each seed to grow into a corm. After 3 years, you should see full size plants and, finally, flowers.
You can also start your seeds indoors. They will need to be cold stratified to imitate winter weather. Wrap your seeds in sphagnum moss and place it in a plastic bag. Put the plastic bag in your refrigerator for 60 to 75 days. This will be the seeds’ “winter”. Then take the plastic bag out of the refrigerator. Remove the seeds from the sphagnum moss and plant them ½ inch deep in a container. They should germinate in about 2 weeks. The seedlings will have a single leaf instead of the characteristic 3 leaves of mature plants.
You can plant your seedlings outdoors after your last frost. It will take about 3 years for your plants to bloom. That’s how long it takes for the corms to grow from the seeds.
© 2020 Caren White