By Jim Lakin, MD, Master Gardener
An outlandish outburst of intense red by the shore of our wetlands tells me its summer and the Cardinal flower is in bloom. Lobelia cardinalis is a member of the bellflower family, Campanulaceae. It’s native to the Americas, from southeastern Canada south through the eastern and southwestern United States and is a Minnesota treasure in my book.
This native gem can be found by the roadside, in ditches or depressions, woodland edges, prairies or savannas, but it is most happy in perpetually moist areas on pond edges, stream banks or wetlands. It can grow as tall as 4 to 6 feet. In the Northern Midwest it blooms for several weeks from mid-summer to early fall with racemes of showy red flowers in 8 inch terminal spikes. It likes full sun but will tolerate partial shade. It is a relatively short-lived perennial but will freely re-seed. Thus, in an undisturbed setting it will put on a vibrant summer show for many years. Although reseeding is its most frequent mode of propagation, bending a stem into the mud and securing it with a rock or stick will sometimes stimulate rooting. When in bloom, it will attract swallowtail butterflies and hummingbirds, serving as an abundant source of nectar. Cardinal flower has few pests and is not particularly attractive to deer or rabbits. Here in Minnesota, mulching the plant in the fall often will help it to winter over.
If you do have a stream or marsh you are thinking of developing with moisture-loving native plants, some great companions to Lobelia cardinalis include: Blue Flag Iris (Iris versicolor), Bottlebrush Sedge (Carex cosmos}, Culver’s root (Veronicastrum virginicum), Great Blue Lobelia (Lobella siphillitica), Joe Pyeweed {Eupatorium maculatum), Marsh Marigold (Caltha palustris) and Swamp Milkweed (Asclepias incarnate). Even without its friends, however, Cardinal flower is a standout.
It is said that Native Americans used the infusions of Cardinal flower for a number of ailments including stomach aches, syphilis, typhoid and worms. It is further alleged that its finely ground root, added to food, acts as an aphrodisiac. I would, however, strongly discourage such usages in that efficacy has not been established and moderate amounts of any part of the plant are poisonous. Merely holding hands with your special someone and enjoying the beauty of Lobelia cardinalis may well suffice.
References:
North Carolina Extension Gardner: Lobelia cardinalis: https://plants.ces.ncsu.edu/plants/lobelia-cardinalis/
Krischik, V, Reed, C, Willey, S., Native Plants for Sustainable Landscapes: Establishment and Management of Lakeshores and Gardens, University of Minnesota Extension Service, St. Paul, MN:, 2000.
Wisconsin Horticulture, Cardinal Flower, Lobelia cardinalis: https://hort.extension.wisc.edu/articles/cardinal-flower-lobelia-cardinalis/