Lobelias of Eastern North America

by cazort

Lobelias of Eastern North America, including Cardinal Flower, Great Blue Lobelia, the annual Indian Tobacco, and many others.

Lobelias are striking flowers that make outstanding landscaping plants or additions to a flower garden. Their bold blue, purple, red, and sometimes white flowers can add a great flash of color in late summer and early fall.

They are relatively easy to grow, especially if you know what conditions they like, and can be grown with little care. Read on to discover the different types of lobelias and their preferred growing conditions.

Cardinal Flower, Lobelia cardinalis

Striking red blooms, prefers wet conditions and part shade, can tolerate full sun or slightly denser shade if conditions are right.

Cardinal flower, or Lobelia cardinalis, is one of the most striking plants native to North America, named for the intense red color of its blooms.  The flowers attract hummingbirds.

Cardinal flower is a prolific bloomer with a long bloom period, typically around late July through early September.  Occasionally certain individual plants will bloom white, or rarely, pink, a natural variation in the flower.

This lobelia strongly prefers wet conditions, such as wetlands and low-lying areas in depressions or along streams.  It can be grown in drier or on more upland sites only if planted in soil or mulch that retains water well.  It can handle quite a lot of shade, but can be grown in sunnier conditions if it has adequate moisture.

It is a perennial and the blooms will often get bolder each year as the plant gets better established, although the plant will become stressed and eventually die out if grown in poor conditions.  Gardeners often find this plant harder to grow than other lobelias, but it will grow vigorously and spread aggressively if conditions are right.

Cardinal Flower Blooms
Cardinal Flower Blooms

Great Blue Lobelia, Lobelia siphilitica

Blue flowers, still prefers wet conditions, but can handle slightly drier and sunnier conditions than cardinal flower.

The great blue lobelia is similar to the cardinal flower in habitat and growing requirements, but it blooms blue.  It is also one of the showiest garden plants.  The two plants can be grown together for varied color.

The growing requirements of the great blue lobelia are similar to that of the cardinal flower, but it prefers slightly sunnier conditions, and is slightly more tolerant of dry conditions.  It is also a bit more general with its habitat preferences, making it easier to grow in most gardens than the cardinal flower.  In many gardens, it will out-compete the cardinal flower, and will spread more aggressively and readily.

The great blue lobelia is mostly bee-pollinated, but if hummingbirds are already in your yard they will typically enjoy its nectar as well.

Great blue lobelia in the wild, Cheltenham Township, PA
Great blue lobelia in the wild, Cheltenham Township, PA
Photo by Alex Zorach

Indian Tobacco, Lobelia inflata

Not closely related to tobacco, this is an annual lobelia with tiny blooms. It grows easily in disturbed soils.

Indian Tobacco, or Lobelia inflata, is not related to tobacco nor can it be safely used as such.  This plant is unusual among lobelias in being an annual, and it also blooms earlier (mid-summer) than most lobelias (late summer to fall).  I recommend it for margins of a garden, areas with poor soil where more desirable plants will not grow.

This plant has very small flowers which are white tinged with blue or lavender.  The flowers look a lot like you took a large lobelia and shrunk it down.  The plant itself is also small, with attractive foliage, with round, slightly fuzzy leaves alternating around the stems, which are usually unbranched, but sometimes branch in response to stress or the top getting cut off.  Rather than blooming in a single spike of flowers, this plant usually blooms in many different isolated flowers in the leaf axils, as the plant continues to grow new foliage. 

Indian Tobacco is easy to grow, especially in disturbed areas with poor soil.  It grows well in clay and rocky soils. It tends to do best in areas where it is exposed to direct sunlight for part of the day, but not the whole day.  In good conditions, it will self-seed, but as it is an annual, unless conditions are right for it, it will eventually die out.   It can often be found growing along chain-linked fences at the margins of lawns, where it evades mowers and weed-whackers.

Lobelia inflata in bloom
Lobelia inflata in bloom
Lobelia inflata plants, growing on disturbed ground
Lobelia inflata plants, growing on di...

Pale-spiked Lobelia (Lobelia spicata)

A white-blooming lobelia, prefering drier conditions than most other lobelias.

The Pale-spiked lobelia, Lobelia spicata, is a little less showy than most lobelias, but still has an attractive spike of white or pale blue flowers.  It is a perennial but tends to be short-lived, less permanent than the cardinal flower or great blue lobelia.  It naturally grows in dry woods, and is sometimes found in prairie, meadow, or savannah habitats where it is surrounded by other, taller vegetation, so its flower stems are weaker.  If grown in a garden, in isolation, it will sometimes flop over.

Lobelia spicata prefers slightly drier conditions than the Cardinal flower or blue lobelia.  It likes rich, loamy soils, but can tolerate slightly rocky soils as well.

(Invasive) Creeping Lobelia - Lobelia chinensis

A creeping lobelia with small, white blooms, introduced from China, has become invasive in Pennsylvania and New Jersey.

Not all lobelias are desirable garden plants in North America.  One species, Lobelia chinensis, called creeping lobelia or Chinese lobelia, has become an invasive weed in Pennsylvania and New Jersey, although it is not currently established in any other states.  It creeps along the ground, and has white, sometimes pink flowers.

I recommend avoiding this plant at all costs because of its invasive potential.  A few of the less ecologically-minded nurseries still sell this plant.  I recommend removing it if you find it in your garden or on your property.

Creeping lobelia, Lobelia chinensis
Creeping lobelia, Lobelia chinensis
How familiar were you with lobelias before reading this page?

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Updated: 06/28/2016, cazort
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