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Lobelia plants' flowers are distinct and recognizable.
lobelia image by Alison Bowden from Fotolia.com

How to Propagate Lobelia From Cuttings

Lobelia is often highly prized by backyard gardeners for its bright flowers, which often attract hummingbirds and butterflies. Lobelia is easy to propagate from cuttings. The trick is to start from new growth, using stems that have not yet flowered.

Fill one or more of the clay pots with the general-purpose potting soil. Dampen the soil but don't get it too wet.

Cut one or more new-growth stems from a Lobelia plant, using the sharp knife or shears. Don't take cuttings from stems that have produced flowers. The cuttings should be about 4 to 5 inches long. Each should contain at least 3 nodes, tiny buds from which new leaves grow. Remove any leaves.

Use the pencil to make a hole in the potting soil and insert a cutting into the hole, covering about half of the cutting. Press the soil firmly around the cutting.

Keep your cuttings in a warm, bright area but out of direct sun. Mist the cuttings two or three times each day with the spray bottle and keep the soil damp but not wet.

Plant the cuttings outdoors when all possibility of frost has passed. Replant the Lobelia when the plant has plenty of new leaves and looks healthy.

How to Prune Lobelia

Watch the lobelia plants as they begin to blossom during the growing season. Often, the lobelia plants seem to tire slightly in the middle of the summer. This is the time to perform pruning to re-energize the lobelia plants.

Trim off as much as half of each lobelia stem to give the plant new growing energy. Cut the stems at any point without concern about specific cutting location.

Fertilize the lobelia plants immediately after pruning. Mix the fertilizer with water according to package recommendations for the size of your growing area. Pour the fertilizer carefully in the soil around the lobelia plants without splashing fertilizer onto the foliage in the process.

Water the lobelia plants immediately after fertilizing to ensure that the fertilizer does not burn the plants.

How to Grow a Cardinal Plant

Plant your cardinal flower in full to partial sunlight and in moist soil supplemented with organic compost or aged manure.

Spread a 1-inch layer of organic material such as compost, manure or leaf mold (humus) on the ground around the base of the cardinal plant. Spread a fresh layer of organic material each year in the spring.

Spread a 2-inch layer of bark mulch around the base of the cardinal flowers to retain soil moisture levels.

Water your cardinal plants two or three times each week during the growing season to supplement rainfall. Water the flowers deeply to soak the soil down to the roots.

Is Lobelia Toxic to Cats?

Lobelia is toxic to cats. Symptoms of ingestion may include diarrhea, depression, vomiting, abdominal pain, excessive salivation and disturbances to heart rhythm.

Lobelia Fast Facts

Genus Lobelia

The genus Lobelia consists of about 400 different species. Well-known types include the cardinal flower (L. cardinalis), Indian tobacco (L. inflata) and the brook Lobelia (L kalmii).


Lobelia flowers are small and tubular shaped. Colors range from shades of red and pink to blue, purple, yellow and white.


Most species like moist, well draining soil that is rich in organic matter. Some will grow in boggy conditions. They prefer full sun to full shade.


Lobelias will readily self seed. Collected seeds benefit from a three-month chill in the refrigerator before germination. Divisions can be taken from the base of the rosettes in the fall.

Herbal Medicine

Several species of Lobelia are used for medicinal purposes. The flowers of L. inflata were smoked by Native Amercians to help ease symptoms of asthma, which is the origin of the name Indian tobacco.

How to Identify a Lobelia

Determine plant height and spread. Lobelias grow from 3 to 10 inches tall and 1 to 2 feet wide, according to the University of Florida IFAS Extension Service. A trailing annual, lobelia forms dense clumps, according to the University of Arkansas Cooperative Extension Service.

Look for flowers. Lobelia plants display bright blue flowers that many times have a white or yellow-hued center, according to the University of Florida IFAS Extension. Some cultivars display flowers in violet, pink, white or purple. Lobelia's five-petaled flowers measure approximately one-half to three-quarters of an inch in length. Two petals make up the top of the flower and three larger petals constitute the bottom, according to the University of Arkansas Cooperative Extension Service.

Observe foliage when trying to identify a lobelia plant. Lobelia plants display simple green, linear leaves on thin stems, according to the University of Arkansas Cooperative Extension Service.

Pay attention to the environment of the lobelia plant. Lobelias require full sunlight to partial shade for healthy growth; a lobelia will not likely be found in a heavily shaded area. Lobelia plants prefer cool climates, rich, well-drained soil and a good deal of moisture, according to the University of Florida IFAS Extension.

How to Grow Cardinal Flower (Lobelia Cardinalis)