Dictionary of Flowers: Lobelia Cardinalis
(Scarlet Lobelia)

Lobelia Cardinalis (Scarlet Lobelia). Image used under a Creative Commons licence with the kind permission of DM and Flickr
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Lobelia Cardinalis (Scarlet Lobelia). Image used under a Creative Commons licence with the kind permission of DM and Flickr

  • Lobelia Cardinalis
  • Common name: cardinal flower, scarlet lobelia
  • Family:  Campanulaceae
  • Category: perennial in USDA zones 2 to 9
  • Height: 24" to 36"
  • Width: 15" to 18"
  • Sun/part shade
  • Blooms: midsummer to early fall
  • Attracts: hummingbirds
  • Growth habit: clumping. Used as a thriller in container combinations
  • Maintenance: medium
  • Soil: fertile, moist, well drained. Water regularly if grown in containers
  • Garden uses: containers, mixed border, water garden, wildflower garden
  • Diseases: leaf spot, rust
  • Pests: slugs and snails

Native North American herbaceous short lived perennial that grows in moist conditions.

It forms clumps of dark green foliage from which bright red flowers grow on spikes. The flowers are tubular and attract hummingbirds.

They thrive in moist locations and bloom late in the growing season, providing nectar for hummingbirds as they retreat to warmer zones.

It has medicinal properties and it was used by the indigenous American Indians to treat a number of ailments.

Lobelia cardinalis requires very moist soil to grow well. Soil pH can be slightly alkaline to slightly acid. Mulching helps retain moisture, as does moisture retaining potting mix when growing in containers.

Water deeply and regularly; never allow the soil to completely dry out. It is a great plant for boggy areas of the garden.

It can grow in full sun to part shade, and even bright shade. Apply a balanced slow release fertilizer once a year in the spring.

Cardinal flower is available in nurseries during summer. It can be propagated by basal cuttings by separating the plantlets from the parent plant and potting them immediately.

IWILLWRITECAPTION. Image used under a Creative Commons licence with the kind permission of NAMEOFFLICKRUSER and Flickr

Cuttings can be taken in late spring or early summer. Treat the cuttings with rooting hormone and plant in perlite. Cover and keep moist.

They root in two to three weeks. Lobelia can also be grown from seed. Sprinkle seed on the surface of moist peat moss. At 75F, they germinate in four to six weeks.

Allow the seedlings to grow four to six weeks before hardening off and planting in their permanent position. Keep the seedlings well watered and fertilize with a weak solution of all-purpose liquid fertilizer.




IWILLWRITECAPTION. Image used under a Creative Commons licence with the kind permission of NAMEOFFLICKRUSER and Flickr

Though not likely to get diseases, leaf spot and rust can be a problem. Treat with a fungicide and remove all affected parts of the plant.

If slugs and snails attack the plant during wet weather, bait as needed. Cardinal flower is deer resistant.

Popular varieties:

  • Lobelia cardinalis - two to four feet tall, rich red flowers
  • Lobelia x cardinalis 'Queen Victoria' - up to four feet long. Dark bronze foliage
  • Lobelia x cardinalis  'Fried Green Tomatoes' - up to three feet long. Blooms the first year planted, hardy variety
  • Lobelia x cardinalis 'Ruby Slippers' - dark red flowers. Hardy to zone 4
  • Lobelia x cardinalis 'Rosea' - pink flowers on three foot long plants. Requires shade

IWILLWRITECAPTION. Image used under a Creative Commons licence with the kind permission of NAMEOFFLICKRUSER and Flickr

Click to see Leucanthemum (Shasta Daisy)
Click to see Lysimachia Lummularia (Creeping Jenny)

Full List of Dictionary of Flowers Entries

Annuals For Containers

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