(Lobelia cardinalis 'Cardinal Flower')
Cardinal Flower is a very-tender warm-weather perennial flower native from S. Canada to Columbia and can be commonly found growing in naturalized areas, woodlands, and wetlands along streams. At maturity, this plant reaches the height of 4'-5' and features 4” finely-toothed, lance-shaped, dark green leaves and erect, terminal spikes of 1-3” cardinal red flowers. This plant can be grown in a container, attracts bees, butterflies, and hummingbirds, is resistant to deer and rabbits, self-sows, and is used as a cut flower!
Genus: Lobelia
Species: cardinalis
Variety: Cardinal Flower
Also Known As: Indian Pink
Awards: Lobelia cardinalis received the Royal Horticulture Society 1993 Award of Garden Merit. It was also selected as the 1982, 1983 and 2001 North Carolina Wildflower of the Year.
Native to: Alabama, Arizona, Arkansas, Belize, California, Colombia, Colorado, Connecticut, Costa Rica, Delaware, District of Columbia, El Salvador, Florida, Georgia, Guatemala, Honduras, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico Southeast, Mexico Southwest, Michigan, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Brunswick, New Hampshire, New Jersey, New Mexico, New York, Nicaragua, North Carolina, Ohio, Oklahoma, Ontario, Panamá, Pennsylvania, Québec, Rhode I., South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, West Virginia, Wisconsin
Introduced into: Trinidad-Tobago.
Grown as: Perennial
Maturity (Blooms): Late Summer-Early Fall
Hardiness: Tender. In the wild, Lobelia cardinalis can tolerate low temperatures up to minus 34 °F.
Light: In colder areas, cardinal flowers appreciate full sunshine. In hotter climates, it will do best with afternoon shade to provide shelter from the intense heat.
Water: Medium to High
Soil Moisture: Medium moisture, Occasionally Wet.
Suitability: Cardinal flowers love moisture, higher humidity levels are ideal; these plants aren't well suited for arid climates.
Attracts Beneficial Insects?: Yes. Bees, Butterflies, Hoverflies, and is resistant to deer and rabbits.
Containers?: Yes. This plant can be used in containers that are 1 gallon or larger. These are not plants that can be moved indoors to grow as houseplants for the winter. Instead, move the potted plants to a sheltered location out of the wind for the winter months.
Maintenance: Low
Height: 3-4”
Spacing: 12”
Sow Depth: On soil surface
USDA Zone: 3-10
Produces: 4” finely-toothed, lance-shaped, dark green leaves and erect, terminal spikes of 1-3” cardinal red flowers.
Garden Uses: Butterfly Gardens, Native Gardens, Pollinator Gardens, Rain Gardens, and Water Gardens.
Known hazards of Lobelia cardinalis: The plant is potentially toxic, but the degree of toxicity is unknown. It contains the alkaloid lobeline which has a similar effect upon the nervous system as nicotine. The sap of the plant has been known to cause skin irritation.
Poison Severity: Medium
Poison Part: Flowers, Fruits, Leaves, Roots, Sap/Juice, Seeds, and Stems.
Spring Planting:
To plant Cardinal Flower in the spring time, the seeds will need to be stratified in your refrigerator for 50 days prior to 6-8 weeks before your areas last frost date. There are three different mediums you could use to stratify your seeds in a refrigerator which is normally determined by the size of the seeds you are stratifying: a potting mix, sand, or a napkin. Choosing the right medium is important because it is impossible to separate super tiny seeds from a potting mix or sand later on.
Stratification by Potting Soil or Sand:
1) Fill a container with moist potting mix or sand.
2) Sprinkle your seeds on top of the potting mix, sand, or on half of your napkin.
3) Mist the seeds with a water bottle and cover your container.
4) Refrigerate your seeds and do not let the potting mix dry out.
5) Remove from refrigerator after 60 days.
Stratification by Napkin:
1) Moisten a napkin using a water bottle.
2) Sprinkle your seeds on only half of the napkin
3) Fold the side of the napkin with no seeds on it over the half of napkin with the seeds on it.
4) Insect the napkin into a zip lock bag and seal it.
5) Refrigerate your seeds and do not let the napkin dry out.
6) Remove from the refrigerator after 60 days.
Germinating Cardinal Flower Seeds:
1) Fill seed starting trays to within 1/4 to 1/2 inch of the rim with moist soil mix.
2) Firm the surface with the back of your fingers, then scatter stratified seeds evenly over the medium.
3) Sprinkle a little additional soil mix over seeds but do not cover fully add a label with the plant name and date.
4) Cover the finished pots with plastic and set them in a warm bright place or under lights at a room temperature of 70 degrees Fahrenheit .
5) Keep the soil moist as the seedlings sprout and develop. Move the pots into direct sunlight to continue growing.
Temperature: 65 - 70F. Ideal 70F.
Average Germ Time: 14 days
Light Required: Yes
Depth: Do not cover the seed but press into the soil
Moisture: Keep seed moist until germination
Transplanting Seedlings into Larger Pots:
1) When your seedlings have two sets of true leaves, pot them up into a larger container filled with a soil mix.
2) After the last threat of frost, harden off the seedlings in the garden for about 10 days.
3) Once the seedlings have been hardened off, you can plant them in the garden.
Fall Planting:
In late fall, direct sow 2-3 of your cardinal flower seeds on the surface of moist humus rich soil that has a pH between 5.5 and 6.5. In colder areas, cardinal flowers appreciate full sunshine. In hotter climates, it will do best with afternoon shade to provide shelter from the intense heat.
Transplant your seedlings into the garden once the soil has warmed after all dangers of frost. Cardinal Flower prefers a moist humus rich soil that has a pH between 5.5 and 6.5. In colder areas, cardinal flowers appreciate full sunshine. In hotter climates, it will do best with afternoon shade to provide shelter from the intense heat. Dig your holes as deep as the pots you are transplanting from and keep a spacing of 1 foot between seedlings. Your soil will need to maintain a medium moisture and even be occasionally wet.
When outdoor temp: 63˚F to 82˚F.
Spacing: 12"
Support: No.
Temperature and Humidity: Cardinal flower can routinely handle the wide range of temperatures across USDA zones 3 to 9. It is known to survive down to minus 34 degrees Fahrenheit, and some zone 2 gardeners have grown it successfully. The named cultivars and hybrids, however, may be somewhat less cold-hardy than the native species plant. Since cardinal flowers love moisture, higher humidity levels are ideal; these plants aren't well suited for arid climates.
Fertilizer: Cardinal flowers generally do not require fertilizer throughout the year. Adding compost and organic material in the late winter or early spring will provide the necessary nutrients for the growing season ahead. This one-time application is generally sufficient for healthy growth.
Pruning: You may want to remove spent flower spikes to keep your plant looking clean and to encourage further blooming. Just keep in mind that this may not allow the plant to self-seed, which could impact next year's colony.
Suggested Varieties
(Asclepias incarnata ‘Swamp’)
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Swamp Milkweed is a native clump-forming perennial flower that grows in wet areas such as swamps and river edges throughout most of the United States. When this plant reaches maturity, it typically grows to 3-4 feet. It has lance-shaped green foliage that measures 3-6 inches in length and produces small clusters of pink flowers that give off a pleasant aroma. This plant can be grown in a container, attracts bees, butterflies, and hummingbirds, is resistant to deer, tolerates drought, is used to make cordage and fabric, self-sows, is both edible and medicinal, and is used as a cut flower!
(Iris missouriensis ‘Wild Blue’)
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Wild Blue Iris is a native annual flower that grows in the wet areas of meadows and mountainous marshes throughout the western United States. At maturity, this plant reaches a height of 2' and features stiff sword-shaped leaves and 2-3” blooms of 6 segmented violet-blue petals with a white and yellow center and dark purple veins. This plant can be grown in a container, attracts hummingbirds, tolerates frost, makes cordage, is resistant to deer, and has medicinal properties!
(Eutrochium maculatum ‘Joe Pye Weed’)
Joe Pye Weed is a native clump-forming perennial flower that grows in coastal regions and damp meadows throughout the northeastern United States. At maturity, this plant reaches a height of 4-7' and features purple speckled branching stems, 8” medium green lance-shaped leaves, and clusters of aromatic florets that are light to dark purple. This plant attracts bees, butterflies, hummingbirds, and pollinating moths, tolerates drought, and has medicinal properties!
(Eutrochium purpureum ‘Sweet Joe Pye Weed’)
Sweet Joe Pye Weed is a native clump-forming perennial flower that grows in prairies, on the edges of woodlands, or on woody slopes throughout central and northeastern United States. At maturity, this plant reaches a height of 2-6' and features purple-speckled branching stems, 8” medium green lance-shaped leaves, and aromatic clusters of florets that are light pink to lavender. This plant attracts bees, butterflies, hummingbirds, and pollinating moths, tolerates drought, and has medicinal properties!