MSU Extension Gardening in Michigan

Many smart gardeners recognize Jack-in-the-Pulpit or Arisaema triphyllum as an unusual and attractive native plant. Some have also wondered if they could help to create more of these woodland cuties in their own shaded gardens. Michigan State University Extension horticulture educators and Master Gardener hotlines are occasionally asked how these plants are propagated. In the wild, not all the seeds have the opportunity. With a little help from you, instead of seeing one or two new Jacks pop up in the spring, there may be more than a dozen.

The first thing to do is determine if your garden can support and nurture Jack-in-the-Pulpit. They grow best in rich soil that is damp in woodlands, boggy areas and stream banks. Enriching shaded soil with additional compost and leaf mold and watering can often create the habitat required for happy Jacks.

In the spring, a solitary shoot comes from the ground and on a mature plant, two sets of leaves and a solitary flower bud emerge. Each leaf is made up of three leaflets. The flower is not like any other many gardeners have encountered. When the bud scales on the flower open, a leaf-like hood called a spathe forms the pulpit portion. It gently folds over the central cylinder of the flower. Inside the column is the spadix that stands like a solitary column with a rounded top. That’s “Jack,” which is classified as a spadix. The flower spathe can range from pale green to dark green and some have maroon and greenish stripes. The entire plant usually grows from 1-3 feet tall. The biggies happen because the plant is older and the soil is particularly damp and rich.

Both male and female flowers are found on the spadix. After the flower is pollinated and the spathe withers, a small, cylindrical cluster of green berries becomes obvious. As the growing season moves along, the berries grow in size. The green berries become orange in August or early September and continue to ripen to a brilliant red. The berries will be below one of the leaves. Leaves may deteriorate, but the berry cluster is an eye-catcher. This is the time to propagate your plant. Berries should be bright red and a bit soft.

Berry cluster ready for harvesting.

During this time, use scissors or small pruning shears to cut the berry cluster free from the plant. The juice can be extremely irritating to many people’s skin, so wear moisture-proof gloves. The berries are also poisonous and cause intense irritation and burning if put into the mouth. Moral of this gardening tale: don’t attempt to eat your garden project.

Each berry could contain anywhere from one to five white seeds. The simplest method is to lightly rake or scratch up an area close to the parent plant or one with suitable planting conditions. Roll the berries gently until the seeds are visible and lightly deposit the seeds on the soil surface. Then, water gently to settle a small layer of soil over the seeds. Use a light coating of leaf mulch over the area, about 1 inch deep. Make sure soil is damp until the ground freezes. Now Mother Nature will take care of a season of cold stratification so the seeds can grow.

If you are bringing seeds indoors to grow, they will not grow unless they are cold-stratified. That means clean seeds are mixed into damp, whole-fiber sphagnum moss in a plastic bag that is sealed and refrigerated for at least 60 days. Plant in a container of soilless potting medium with seeds buried no deeper than 0.25 inches. Keep damp and germination will take place in about two weeks if the area is not too cold. Most growers keep them indoors for two years before moving the seedlings outdoors.

When examining the two methods of propagation, it is Mother versus bother. Mom wins for most smart gardeners.