The bright red of cardinal flower (Lobelia cardinalis) looks like someone pricked summer and made it bleed at the edges. Brilliant fire-engine red petals fringe the tall, slender stalks of this water-loving wildflower, adding drama and glamour to a late-summer garden. This is one of the brightest of all wildflowers, and it’s a flashing neon sign for ruby-throated hummingbirds, who begin their journey south while cardinal flower blooms. When the heartbeat of summer is gone and autumn leaves are about to turn, the vivid petals of Lobelia cardinalis finally fade.
Common name: Cardinal flower
Botanical name: Lobelia cardinalis
Plant type: Perennial
Zones: 2 to 8
Height: 2 to 4 feet
· Sun: Full sun if kept damp; otherwise, best in part shade
· Soil: Average
· Moisture: Moist to boggy
· Mulch: Mulch to preserve moisture in the soil.
· Pruning: None needed.
· Fertilizer: None needed.
· By seed or by division
Pests and diseases
· Vulnerable to smut, rust, and leaf spots.
· Common pests include slugs.
· Add plenty of organic material to the soil and mulch cardinal flower heavily.
· Plant in front of ferns or dark-foliaged plants to highlight the red flowers.
· Use near ponds or other water features, in a bog or wetland setting, or in that low spot in your yard that’s always damp.
· Cardinal flower is a favorite of hummingbirds, butterflies, and bees.
· A handful of cultivars of Lobelia cardinalis are available, including the white-flowered ‘Alba’, the pink ‘Twilight Zone’, and ‘Angel Song’, which has salmon-colored blooms.
All in the family
· There are about 370 species of lobelia—the genus contains perennials, annuals, and shrubs from both temperate and tropical regions. In your hanging baskets, you may have a Lobelia erinus cultivar—these are low-growing, sometimes trailing, plants with blossoms in shades of blue, pink, red, and white.
· Also in the Campanulaceae family are bellflowers (genus Campanula) and balloon flowers (genus Platycodon).
(Text by Elizabeth Noll, photo of Lobelia cardinalis courtesy of Missouri Botanical Garden’s Kemper Center for Home Gardening)