How to Plant & Grow Jack-in-the-Pulpit (Arisaema triphyllum)


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A close-up of jack-in-the-pulpit and its spathe
Jack-in-the-pulpit has a floral hood that protects the spathe. Geoffrey.landis, CC BY-SA 4.0, via Wikimedia Commons

Arisaema triphyllum is an herbaceous perennial plant that boasts a lot of character. Its delicate features have made it a favorite wildflower for moist gardens. This species is fondly known by many curious names, such as jack-in-the-pulpit, brown dragon, Indian turnip, and bog onion. It is classified under the Araceae family of aroids. This family includes a highly diverse selection of thousands of flowering plants, yet they are all unified by their specialized inflorescence morphology. 

Among aroids, jack-in-the-pulpit stands out for having a vivid and distinctly patterned floral hood, which protects the spadix. In this sense, “jack” refers to the green to purple-colored spadix and “pulpit” undoubtedly refers to the hood, which botanists would call a ‘spathe’. The inner part of the spathe is usually distinguished by light green stripes and contrasted by a darker leaf coloration. Many subtle variations exist, however.

Each individual plant produces just two leaves each year. Each is further divided into three glossy, bright green leaflets that arise on the ends of foliar stems. The leaves often act as an umbrella, providing additional protection to the specialized flowers each summer. Stems are borne by tuberous root systems with bulb-like corms. This species is native to eastern North America, where it occurs as far north as Nova Scotia to as far south as Florida.

Facts, Benefits & Uses of Jack-in-the-Pulpit

Jack-in-the-pulpit berries
Pollinated females produce large, bright red berries that ripen through the summer. MrGreenBean, Public domain, via Wikimedia Commons

Interestingly, the specialized flowers of jack-in-the-pulpit start off as male. As the plant grows larger, it eventually produces female flowers. This phenomenon is called sequential hermaphroditism and has an adaptive significance in the Arisaema genus. Larger pollinated females produce more robust berries, which ripen through summer and turn bright red. Principal pollinators include fungus gnats (Mycetophilidae) and beetles, which can be trapped in the spathes of female flowers.

Jack-in-the-pulpit tends to go dormant in late summer or fall, just after the fruits have ripened. The berries attract a wide assortment of mammals and birds, which are instrumental in dispersing their seeds.

It’s important to note that the entire plant has a high toxicity profile and must be handled with caution. Calcium oxalate content is most concentrated in its roots, which can cause painful symptoms if ingested. Native Americans found use for the roots, using them as both a cure-all and a disguised poison for their enemies. They would dry, slice, and cook them into crisps or they would include them in potent treatments for sore eyes, snake bites, bronchitis, and rheumatism.

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Jack-in-the-Pulpit Fact Sheet:
PLANT TYPE
Herbaceous perennial
HARDINESS ZONES
USDA 4 – 9
LIGHT REQUIREMENTS
Full sun to partial shade
BLOOM COLOR
Green, purple
BLOOM PERIOD
April to May
MAXIMUM GROWTH
2 feet (61 cm)
PLANTING DEPTH
1/2 inch (seeds); 6 inches (corms)
WATER QUALITY
Slightly acidic to neutral

Jack-in-the-Pulpit Growth, Hardiness & Climate

Jack-in-the-pulpit in a forest
Jack-in-the-pulpit is usually found in woodlands and bogs, and favors moist and loamy soil. IvoShandor, CC BY-SA 3.0, via Wikimedia Commons

In the wild, colonies of A. triphyllum are mostly found in woodlands or bogs. This species is used in mass plantings along shaded borders or next to water features. Its roots favor consistently moist and loamy soil but are averse to extended periods of wetness. Unless the substrate is appropriate, an exposed position can cause the shoot and leaf systems to dry out.

Hardy to USDA zones 4 – 9, this plant enters an early and lengthy period of dormancy. It can become dormant as early as summer, after which vegetation will not be produced again until spring next year. This indicates that the plant benefits most from mild temperatures in spring.

To sustain year-round interest in the garden, it should be planted next to species with above-ground features that are sustained through summer and winter. Ideal plants include lungwort (Pulmonaria officinalis), heartleaf brunnera (Brunnera macrophylla), and impatient lucy (Impatiens walleriana).


How to Plant Jack-in-the-Pulpit

Jack-in-the-pulpit seeds
You can plant jack-in-the-pulpit with seeds, though it requires patience as a high portion of seeds are unviable. Hardyplants at English Wikipedia, Public domain, via Wikimedia Commons

Jack-in-the-pulpit can be planted using its seeds or full-sized corms. As a high portion of seeds tend to be unviable, propagation via root division is more successful. Regardless, if you have the patience to harvest seeds, you can sow them directly outdoors or in an indoor germination setup. When extracting the seeds from fruits, make sure to use gloves. Seeds sown indoors must be cold stratified for 2 – 3 months in a bag with sterilized sphagnum moss prior to being planted. They should be buried, about half an inch (1.3 cm) below the surface, in sterilized moist soil or in a commercial potting mix.

Once seedlings are large enough, they should be transplanted into their own individual pots. Situate pots in a greenhouse or cold frame and keep the soil moist. It may take a few years for the young plants to produce corms that are stable. Those with corms that reach a diameter of at least an inch (2.5 cm) may be planted in their permanent outdoor positions. To minimize the stress of transplantation, make sure to outplant when the root system has entered dormancy.

If propagating using corms, be extra cautious as they are highly poisonous in raw form. Corms can be planted directly outdoors, to fill in spaces between existing plants. They should be situated around 6-inches (15 cm) deep in fairly moist soil. Make sure the root-producing side of each corm is facing downward. To deter pests from damaging young shoot systems, you can place eggshells, diatomaceous earth, or gravel around the patch of corms. Small containers filled with beer may successfully keep pests away as well!


How to Care for Jack-in-the-Pulpit

Jack-in-the-pulpit in bloom
Jack-in-the-pulpit is remarkably easy to care for and has a flowering period of up to 35 days! Jason Hollinger / CC BY 2.0

A. triphyllum is remarkably easy to care for if ambient conditions are optimal. Simply make sure to keep the ground moist and fertile. A layer of mulch through summer and fertilizer or compost application in the succeeding spring can enrich corms, allowing them to produce more fertile flowers.

During the first few years of growth, young corms may be unable to yield flowering shoots, so don’t be too worried by the lack of distinct spathes. When they do flower, you’ll be pleasantly surprised by the longevity of the blooms. The Arisaema flowering period can last for up to 35 days!

This species is largely disease and pest-free, though slugs may occasionally nibble on the stems. It is also deer and rabbit-resistant. As the roots enter dormancy, make sure to cut down any decaying foliage and shoots.


How to Winter Jack-in-the-Pulpit

As this species is native to areas that experience cool temperatures, its corms are able to tolerate being left outdoors through winter. They will not require special attention and should ideally be left undisturbed (if being cultivated as perennials) as temperatures drop. Tend to the area with dormant plants by removing any decaying material and keeping potential pests away.

If you intend to divide mature corms or treat the plant as an annual, you can dig out dormant corms in late summer or autumn. Mature corms and divisions can then be replanted before they exit winter dormancy.


Is Jack-in-the-Pulpit Invasive or Toxic?

Despite its capacity to reproduce both vegetatively and sexually, jack-in-the-pulpit is not known for being an invasive plant. Though mature corms may spread to form large underground networks, the prolonged periods of dormancy may prevent the plant from competing with more vigorous year-round native species. Moreover, successful sexual reproduction relies on live pollinators as pollen cannot be dispersed through aerial means.

Though non-invasive, it would be prudent to be knowledgeable about this species, especially in its native zones, due to its toxicity. It can often be mistaken for poison ivy, which can be a good thing as this would dissuade people from handling the plant. When ingested, the high calcium oxalate concentrations in the plant’s tissues can cause severe irritation and even lead to the obstruction of airways. If your garden is frequented by children or pets, make sure your jack-in-the-pulpit patches are blocked off.


Is Jack-in-the-Pulpit Edible? Will Animals Eat it?

Despite its high toxicity potential, the roots of this plant are considered edible by some indigenous groups. A lengthy process of preparation is required to fully neutralize the crystals, however, and should only ever be attempted by expert foragers. If prepared correctly, the corms can even be ground to flour and used to bake sweets. In raw form, the calcium oxalate crystals are said to resemble the taste of peppers.

Strangely, wild animals seem to be able to consume some raw parts of the plant without experiencing negative symptoms. Deer may occasionally graze on the berries or the corms of the plant. Black bears, turkeys, and wild birds tend to favor the berries as well.


Where to Buy Jack-in-the-Pulpit & Seeds? (UK & US)

Arisaema triphyllum can be purchased as seeds, corms, bare-root, or potted plants in nurseries throughout its native range. The availability of each type of growth is seasonally affected due to this species’ dormant phases. Varieties that are chiefly cultivated for ornamental purposes include A. triphyllum ‘Starburst’, ‘Black Jack’, and ‘Mrs. French’.  

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