Cardinal Flower – Lobelia Cardinalis: Not-so Edible & Medicinal Uses of the Reddest Flower of Wild Plants

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Cardinal-flower (lobelia cardinalis) is a similar but less potent medicinal as its close relation lobelia inlata, and it’s similarly inedible. But it’s got one of the most stunning, if not the most stunning, red flowers of all of Ontario’s native plants.

In Haliburton county, cardinal flower (lobelia cardinalis) is an uncommon but memorable sight on the banks and wet edges of rivers and streams. Robin found a patch on the edge of a beaver pond on the 100 Acres. I saw my first patch along the rugged streamside trail to High Falls in South Algonquin Park.

Cardinal Flower – Lobelia Cardinalis
Cardinal Flower – Lobelia Cardinalis

There are two other lobelia recently noted here in Haliburton county. Water lobelia (l. dortmanna) is common in shallow water or half emerged in small lakes. And Indian-tobacco (l. inlata) is perhaps common and found in moist or dry roadsides, mixed forests and open rocky terrain. They are both more understated in their looks..

As is a fourth lobelia, the rare pale-spike lobelia (l. spicata), which was spotted on a high grassy hill with a few trees and shrubs here in the past; however, there are no recent sightings.

Great blue lobelia (l. siphilitica) is unlikely to be found in the wild in Haliburton county, but it’ll grow here and it’s also a stunner, only in blue.

Cardinal flower is more common on the east side of Algonquin Park. But if you visit the west side of Algonquin park you may be able to find the rare Kalm’s lobelia (l. kalmii).

The lobelias mentioned in the above paragraphs are all native. But there are garden varieties that are nonnative. These plants are in the harebell family with bellflowers, which include the purple invasive creeping bellflower that can be spotted choking out other plants along roadsides here.

Not-so Edible Uses of Cardinal Flower

Cardinal Flower – Lobelia Cardinalis
Cardinal Flower – Lobelia Cardinalis

Lobelia species are poisonous, so just eye candy.

Medicinal Uses of Cardinal Flower

Cardinal Flower is primarily said to support these body systems:

  • Digestive
  • Integumentary
  • Muscular
  • Respiratory
  • Urinary

Medicinal tags include Anthelmintic, Antispasmodic, Diaphoretic, Diuretic, Emetic, Expectorant, Nervine, Sedative and Simulant. See Medicinal tag key for more information.

Common usage includes as a less potent version of Indian tobacco, which we covered months ago. Primarily, they both contain the alkaloid lobeline which relaxes smooth muscle tissues. But both lobelia species can cause a coma or even death if overdosed. More details on their usage plus safer alternatives can be found in the Indian tobacco article.

Cardinal flower first year rosettes
Cardinal flower first year rosettes

Growing Lobelia Cardinalis

I have my cardinal flower patch paired with great blue lobelia beside a small pond. Jewelweed recently volunteered next to them. They all bloom around the same time, late summer, and together give me a striking red, bright blue and fiery orange pondside. The hummingbirds and bumblebees love this neck of the 1 Acre. White turtlehead (chelone glabra) is another recommended pairing.

Cardinal flower prefers full sun, but you can also grow it in partial shade. It mainly needs moist soil, ex. a rain garden or natural pond setting. You will need organic material in the soil, as sand will drain too fast for wetland species.

You can start from seed or plants can be divided in spring or fall. I got my rosettes from ONPlants. This is one of those plants you’ll likely need to reseed or replant to keep it thriving. I often pass on these sorts, but red is my favourite colour. It’s a wonderful plant for attracting hummingbirds. It’s also a beautiful candidate to introduce native plants to folks you know who always put out hummingbird feeders (who also happen to have a suitable damp spot on their property!)

There are some bigger native plants that serve even more diverse wildlife that will work in the same wet areas as cardinal flower, like joe-pye weed, blue flag (planted in the pond), blue vervain, common milkweed and swamp milkweed. These are taller, so I have them north of my lobelias. And I use containers around my pond for some of the more aggressive spreaders. A wonderful book for planning your natural pond is Building Natural Ponds: Create a Clean, Algae-free Pond without Pumps, Filters, or Chemicals.


Avoid use if pregnant or diagnosed with hypertension.

The USDA labels it as poisonous and misuse can be fatal.

And the Usual Cautions:

1) Most medicinal herbs, if edible, are meant to be eaten in moderation, even sparingly. Some require extra preparation. Tannins are toxic if consumed in excess.

2) People can be allergic or sensitive to nearly any plant; try new herbs one at a time at your own risk. For instance, saponins commonly cause stomach upset.

3) For medicinal use, I must recommend receiving a diagnosis and working with a reputed health care provider. I generally do not post specific treatments and dosages because I think that is best between you and your health care provider, and ideally monitored.

4) Anyone pregnant, nursing, or taking prescription drugs should talk to a health care professional before adding new food items to their diet.

5) Many plants have look-a-likes, and sometimes they are poisonous.

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