Lobelia Cardinalis [low-BEL-ee-a, kar-dih-NAL-iss] is a flowering plant species from the Campanulaceae or bellflower family.
Native plants to North Americas, where it is distributed from southeastern Canada, southwestern and eastern United States, Central America, and Mexico, to northern Columbia.
Its native habitat is along stream banks, roadside wildflower, prairie, meadows, and more.
It is also known by its synomyn Lobelia fulgens.
The common name cardinal flower emerged after the plant was introduced in Europe in the 1620s, and probably due to the similarity of colors between its flowers and the vesture of Roman Catholic Cardinals.
Cardinal Flower Care
Size & Growth
The herbaceous perennial Lobelia plant naturally grows in moist places, such as alongside streams, swamps, and springs and typically reaches the height of 2’ to 4’ feet.
When grown in nurseries or gardens, the plant needs to be provided marshy conditions to ensure proper growth.
L. Cardinalis feature 2’ to 3’ feet long un-branched stalks and finely-toothed, rough-textured, dark-green leaves, which have fine hair on the undersides and are arranged in an alternating pattern.
The light-green central stem is hairy; sometimes sparingly and sometimes densely.
The plant is short-lived, but, it spreads through self-seeding, in ideal growing conditions.
It is hardy in USDA hardiness zones 3-9.
Flowering and Fragrance
In late summers, the plant starts producing striking showy raceme of cardinal-red flowers in the form of erect terminal spikes, which are highly appealing and are the most noticeable feature of lobelia cardinalis.
However, they are not fragrant.
The flowers are long (about 1.5” inches), tubular and two-lipped with three lobes forming the lower lip and two lobes forming the upper one.
Some varieties of the plant are also known to produce white and rose-colored flowers, but they are not as common as the scarlet red ones.
During new plants’ bloom time, they start opening from the bottom of a flower spike.
The blooming period lasts until early fall.
Light & Temperature
While lobelia tolerates full sun in areas where summers are not too hot, such as northern climates, it enjoys some afternoon partial shade or part shade in extremely hot weather.
Appreciates part afternoon shade in hot summer climates of the lower Midwest and South.
Watering and Feeding
L. fulgens is a moisture-loving plant and cannot grow well if it doesn’t get an adequate amount of water.
While regular watering is essential, it should not be left in standing water as it reduces the life of the plant.
Fertilize the established and actively growing lobelia plants with a good all-purpose fertilizer, once a month.
Soil & Transplanting
When cultivated, the plant requires deep wet soil, rich soil, and moist soil.
Moisture is highly important for this plant; the soil should never be allowed to dry out. It easily adapts to different types of soils, including gravel, loam, and sandy loam, if it contains organic matter and remains consistently moist.
Although the cardinal flower plant is perennial, it may not live for long if the right kind of soil is not provided.
Transplantation is the best method for establishing this species of bellflower family because the tiny size of its seeds and highly fragile nature of young seedlings make it a little harder to grow from seeds.
Divide after every 2 to 3 years.
Grooming and Maintenance
Cardinalis flowers are low-maintenance plants and do not need much care apart from maintaining a consistent supply of water to keep the soil moist.
Applying root mulch is recommended in cold weather to retain soil moisture and protect the roots from heaving.
Deadheading helps to maintain a neat appearance, prevent undesired re-seeding, and to encourage re-blooming.
How To Propagate Red Lobelia Cardinal
L. fulgens is propagated by seeds, plant division, and cuttings.
Seeds of lobelia plant are sown from late winters to mid-spring.
Sow the ripe seeds in a tray or pot filled with a good quality seed sowing compost and place it at a warm place, sealed in a plastic bag.
Alternatively, use a propagator to provide warm temperature, essential for seed germination.
The ideal temperature range for germination of seeds is 65° – 75° degrees Fahrenheit (18° C – 24° C).
Let the seedlings grow a bit, so they are easy to handle and then transfer to cell trays or pots.
While transplanting, make sure to plant 5 to 6 seedlings in one pot.
Place the pots in a slightly cooler area.
Take softwood cuttings in mid-summer or divide the young plants, which develop around the older, mature ones, in late summer.
Cardinalis Lobelia Pest or Diseases
While the plant is not prone to catching any serious disease, it is advised to watch out for slugs and snails as they may cause damage to the foliage.
The larvae of a polyphagous fly and the caterpillars of a moth may also mine and feed on the leaves, respectively.
The nectar of the flowers makes Lobelia plants attractive for Hummingbirds and swallowtail butterflies.
The plant contains many alkaloids, which may potentially be toxic to humans.
Hence, the plant is not safe for consumption.
Red Lobelia Uses
Cardinal flower plant is a wonderful addition to water, rain garden, pollinator gardens, and shade gardens and is also ideal for planting alongside ponds and streams.
Makes for great cut flowers. It is also great for adding height and color to borders, provided its soil remains uniformly moist, year-round.
It is also used for certain medicinal and recreational purposes in some areas.
The ground roots of this Native American wildflower were traditionally used for aphrodisiacs and love potions.
Good companion plants include:
- Great blue lobelia – Lobelia siphilitica
- Asclepias incarnata (Milkweed plant)