Gardening Flowers Perennials How to Plant and Grow Cardinal Flower The vibrant red flower spikes of this short-lived perennial are hummingbird magnets. By Nadia Hassani Nadia Hassani Nadia Hassani is a gardening and food writer with more than two decades of hands-on gardening experience in vegetable and fruit gardening, landscaping with native plants, and garden design. Learn about BHG's Editorial Process Updated on April 5, 2024 In This Article View All In This Article Where to Plant Planting Tips Care Pests and Problems Propagation Types Companion Plants FAQ Trending Videos Close this video player The cardinal flower is a tall perennial lobelia that is native to the eastern United States and not to be confused with the low-growing, often blue annual lobelia. Its brilliant, showy red blooms first mature in late summer and continue into midfall. The flower spikes are magnets for hummingbirds and great for wildlife gardens. The lance-shaped, shiny foliage is a handsome dark green. These colorful red flowers, named after the red robes of Roman Catholic cardinals, are a wonderful choice for landscaping around ponds and streams—anywhere the soil is consistently moist. Lobelia even loves downright wet conditions, making it a top choice for bog and rain gardens. Cardinal flower is toxic to humans and pets. Cardinal Flower Overview Genus Name Lobelia cardinalis Common Name Cardinal Flower Plant Type Perennial Light Part Sun, Sun Height 4 to 5 feet Width 1 to 2 feet Flower Color Red Foliage Color Blue/Green Season Features Fall Bloom, Summer Bloom Special Features Attracts Birds, Cut Flowers, Good for Containers Zones 4, 5, 6, 7, 8, 9 Propagation Division, Seed Where to Plant Cardinal Flower Ideal places for cardinal flowers are wetlands, moist woodlands and shade gardens, wet meadows, along streams or ponds, as well as near water gardens and rain gardens. As long as the soil offers the required moisture, it can also be planted in borders or pollinator gardens to attract hummingbirds and butterflies. Cardinal flower is especially striking when planted in groups or drifts. After the plant has set seeds, the flowering stem and the roots die back but new offsets soon form and root rapidly. These offsets are easily damaged so make sure not to step on them or bury them under a thick layer of mulch in the fall and winter. How and When to Plant Cardinal Flower Plant nursery-grown cardinal flowers in the spring. Dig a hole about twice the size of the nursery pot and deep enough to accommodate the plant’s tap root. Place the plant in the hole and fill in original soil to the top of the root ball. Gently tamp down the soil. Water thoroughly after planting and keep the soil moist in the absence of rain. In a mass or group planting, space plants about 20 inches apart. Cardinal Flower Care Tips If planted in a location where the soil is consistently wet, cardinal flower is a low-maintenance plant. Light In northern climates, cardinal flower thrives in full sun. In more southern locations, the plant does better when protected from the scorching sun in a spot with partial afternoon shade. Soil and Water The most important soil property for cardinal flowers is consistent soil moisture. The soil should never be allowed to dry out. The plants even withstand brief flooding. The soil should also be rich in organic matter so amend it before planting if necessary. A pH between 6.0 and 7.5 is ideal. To help retain soil moisture, spread a 1-inch layer of mulch around the base of the plant. Temperature and Humidity Cardinal flower withstands both freezing winters as well as hot summers as long as it is given sufficient moisture. To protect the rhizomes with their small rosettes of leaves against the winter cold, use a 1-inch layer of hardwood mulch for insulation, which also protects the plant against frost heave. Fertilizer There is no need to feed cardinal flowers with a commercial fertilizer—working a layer of compost or other organic matter into the soil around the plant in early spring is sufficient. Pruning Removing any brown leaves or spent flowers is optional and mainly done to keep the plant looking tidy. If you would like to plant to self-seed, do not remove the flower stalks with the seed heads in the fall but wait until the spring. When you cut back the plant, make sure not to damage the basal growth (the bottom layer of foliage). Potting and Repotting Cardinal Flower The ideal place for cardinal flower is in the landscape but it is possible to grow it in containers. Use a container with at least 1-gallon capacity or larger and make sure it has adequate drainage holes. Fill it with well-draining potting mix and water it frequently to keep the soil constantly moist. Potted cardinal flowers overwinter outdoors but the roots should be insulated against the cold by moving the pots to a sheltered outdoor location, burying the container in the ground, or placing it in a large container filled with mulch, sand, or another insulating material. Pests and Problems Cardinal flower is unbothered by serious pests and diseases. You might find snails and slugs feeding on the foliage. Deers, rabbits, and other herbivores tend to avoid the plant. How to Propagate Cardinal Flower Cardinal flower is easily propagated from seed although collecting the seeds from hybrid varieties is not recommended as they won't produce plants that are true to the parent. Plant the seeds in small pots of flats outdoors in mid- to late winter; they require 60 days of cold stratification to germinate. Alternatively, you can also place the seeds in a sealed plastic bag with a damp paper towel in the fridge for 60 days, then plant them in the early spring outdoors. Do not cover the seeds with soil; they need light to germinate. Types of Cardinal Flower Queen Victoria Lobelia The flowers of this Lobelia cardinalis cultivar are a deeper red than the species and the foliage has a dark burgundy color. It grows 3 to 4 feet tall and 1 to 2 feet wide. Zone 4-9 'Fan Salmon' Lobelia Lobelia x speciosa 'Fan Salmon' is a bushy, compact hybrid with warm salmon-pink flowers and contrasting bronze foliage. It grows 2 feet tall. Zone 4-8 'Fan Scarlet' Lobelia Lobelia x speciosa 'Fan Scarlet' has a similar growth habit and size as 'Fan Salmon' but scarlet-red flowers. The foliage is also bronze-colored. Zone 4-8 Blue Cardinal Flower Also called great blue lobelia, L. siphilitica is a short-lived perennial lobelia with large, deep blue-violet flower spikes. It is native to a vast geographical area, ranging from Maine to Georgia west to Texas, Colorado, Wyoming, and the Dakotas. It blooms late in the season and provides nectar to bees and butterflies. Zone 4-9 Cardinal Flower Companion Plants Swamp Milkweed It does not require a swamp to grow swamp milkweed (Asclepias incarnata) but this key host plant for monarch butterflies thrives in consistently moist soil though it also grows in drier sites. Its pink to rose-purple flowers mature in midspring and last into early fall. Swamp milkweed grows up to 5 feet tall and needs full sun. Zone 3-9 Culver’s Root With a height of up to 8 feet and long spikes of densely clustered flowers, this native plant stands out in the landscape. The white, lavender, or blue blossoms of Culver's root appear for several weeks in midsummer. Culver’s root needs a spot in full sun where the soil stays consistently moist for extended periods. Zone 3-9 Hardy Hibiscus Tropical-looking but actually a shrub for northern climates, hardy hibiscus is sure to impress with its vibrant, dinner plate-size blossoms and deep reddish-green to burgundy foliage. The large blooms last just a day or two before being replaced with new flowers. It thrives in moist to wet soil and full sun. Zone 4-9 Frequently Asked Questions Is cardinal flower an annual or a perennial? There are more than 400 Lobelia species, both annuals and perennials. Cardinal flower is one of the perennial species, though it is short-lived. Does red cardinal flower spread? The plant does not spread through its roots but by self-seeding, though not in an aggressive way. Was this page helpful? Thanks for your feedback! Tell us why! Other Submit Sources Better Homes & Gardens is committed to using high-quality, reputable sources—including peer-reviewed studies—to support the facts in our articles. Read about our editorial policies and standards to learn more about how we fact check our content for accuracy. Cardinal Flower. ASPCA. Lobelia cardinalis. North Carolina State University Cooperative Extension.