sun, part-sun, part-shade
acid, neutral, alkaline, rich, loam, clay, sand
July, August, September
3, 4, 5, 6, 7, 8, 9
It is impossible not to do a double take when you spot a Lobelia cardinalis in bloom during the heat of summer. Its vivid red is so conspicuous it hardly seems possible nature could produce a color that intense. The plant has a vertical habit, with deep-green, lance-shaped, coarsely serrated leaves that are up to 6” long and predominantly basal. It produces an unbranched central stem that terminates in a flowering spike that can be up to 2’ long, bring the plant’s total height up to 3 to 4’. The flowers are tubular, intensely red, and up to 1 ½” long. You will enjoy this species’ long blooming period that can occur from late summer to early fall, and lasts about 1 ½ months.
Lobelia cardinalis is very adaptable, with the only requirement being that the soil not dry out for extended periods. It can grow in full sun just as well as in part-shade where it gets exposed to as little as 2 hours of direct sun per day. Just keep in mind that the more sun it is exposed to, the higher its water needs will be. It is not particular about soil and will thrive in sandy loam as well as in clay soil. To be accurate, this is not a true perennial: the above ground parts as well as the roots of each individual plant will completely die after it blooms, but not before producing offshoots that will in turn ensure its perennial presence. It is therefore important to not heavily mulch the base of the plants in fall, or let a lot of leaf litter accumulate, because these offshoots will need to be exposed in order to survive. Great around water features and in rain gardens, cardinal flower can also be a showy addition to perennial gardens and woodland borders. Zones 3-9
Lobelia cardinalis is attractive to butterflies and hummingbirds. It is moderately deer resistant. It would be easy to assume that Lobelia is a reference to a lobed feature common to all species within the genus. In fact, the lower lip of L. cardinalis flowers is indeed conspicuously lobed. However, you would be making a wrong assumption. The genus is named after Flemish physician and botanist Mathias de l’Obel (1538-1616), aka Matthaeus Lobelius (latinizing names was a thing back then). The root of the specific epithet cardinalis goes back to the noun cardo, meaning “hinge”. From there it came to signify something pivotal and important, hence by the late Middle Ages the word cardinalis was used for the highest ranking church officials after the Pope. So, and I’m sure you’d guessed it before this long trip down memory lane, both the specific epithet cardinals and the common name cardinal flower are a reference to the fashionably-red garb sported by Cardinals of the Catholic Church.