Does Arisaema Triphyllum Need a Cold Period?

Characteristics

• Jack-in-the-pulpit is a native woodland plant that's about 1 foot tall and produces one or two 3- to 4-inch-tall flowers each year. The flower is made up of a central spadix, or spike, that holds the many tiny, true flowers. It's surrounded by a leafy structure called a spathe that has a tubular base and a tall, drooping hood, making up the pulpit. The spathe is usually striped in light green and yellow, with purplish-green markings. In late summer, the flowering part of the plant produces a cluster of red berries.

Climate

• The jack-in-the-pulpit plant fades, and its above-ground parts usually disappear in mid to late summer, leaving behind only the part bearing berries. The plant needs this period of dormancy, which extends through winter's cold period, to rest and prepare for new growth the following spring. The warmest portion of jack-in-the-pulpit's natural range covers USDA zone 9, where winter temperatures often drop below freezing and may be as low as 20 or 25 degrees Fahrenheit for short periods. The plant doesn't do well in warmer areas above zone 9, where winter temperature usually stays above freezing, because the warm winter temperatures interfere with its dormant period.

Site Selection

• If you live in a warmer portion of this plant's range, you can help ensure that it gets the winter chill it needs by planting it in a spot that's relatively cool during winter. An ideal spot is in a north- or northeast-facing garden that doesn't get warm sun in winter. The plant also needs full or partial shade for the entire day and tends to develop scorched foliage and flowers when grown in too much hot sun. Mulching the plant well in fall also protects the plant from freeze-thaw cycles in winter, which can cause warming of the roots, followed by rapid and potentially damaging drops in temperature. The roots of this plant contain a toxic substance called calcium oxalate, so it's not a good choice for an area frequented by pets or small children.

Other Needs

• A jack-in-the-pulpit plant needs organically rich soil, such as under trees or large shrubs, whose cast-off leaves slowly degrade to provide organic matter to the underlying soil. You can also increase the organic content of your planting area by mixing in compost at planting, and adding extra compost to the area during the first few years is also helpful. The plant needs constant moisture and thrives in a moist, well-drained spot, but choose a site that isn't rich in clay and tends to stay soggy, or add some sand to the planting area to improve its drainage.