Arisaema, also known as cobra lily, is an herbaceous perennial plant native to North American woodlands. Another common name for the plant is jack-in-the-pulpit, due to the appearance of the flowers. The spathe, or pulpit, wraps around the spadix, or jack, resulting in what resembles a man standing behind a covered lectern. Arisaema has been referred to as bizarre, beautiful and everything in between, but has always been valuable for the interest it adds to the home garden. Arisaema plants are easy to grow in every hardiness zone with just a little care and attention.
Plant arisaema tubers or plants in early spring. Choose a planting location that receives full to partial shade and has rich, moist and well-drained soil. Plant about 3 to 6 inches deep, depending on the size of the tuber, and space plants 4 to 5 inches apart for the best results.
Water arisaema thoroughly just after planting, and continue watering tubers once per week until growth emerges. Water established arisaema plants twice per week or enough to keep the soil consistently moist at all times. Increase watering to once per day during very warm or drought-like conditions.
Feed arisaema plants once every two weeks using an all-purpose garden fertilizer. Refer to the manufacturer's instructions for proper dosage and apply at half strength. Cease feeding after flowering and when the leaves begin to wither.
Remove spent flowers after blooming by pinching them off at the base. This will prevent self-seeding, which can become a problem if the flowers are not removed. No further pruning of arisaema plants is required.
Apply a 3- to 4-inch layer of mulch around the base of arisaema plants in fall before the first frost of winter. This will protect the tubers from cold temperatures. In zones 1-3, dig up the tubers and store in damp peat moss in a freezer bag. Place the bag in the refrigerator and replant when all danger of frost has passed in spring.