Lobelia cardinalis L. is the correct and accepted name for this species of Lobelia. It was described by Carl von Linnaeus in Species Plantarum in 1753.
The genus, Lobelia Plum. ex L., was also described by Linnaeus in the same publication but it was originally named by Charles Plumier. Most sources just list the genus name as Lobelia L., but Plants of the World Online list the name as Lobelia Plum. ex L. Mr. Plumier was considered one of the most important botanical explorers of his time and was appointed botanist to King Louis XIV of France. He was born in 1646 and died in 1704. To read more about him, click HERE.
Plants of the Word Online list 433 accepted species of Lobelia as of 2-21-19. There were 425 when I wrote this page… Hmmm… Well, POWO is still uploading data and botanists are continually tweaking around with plant names.
I had not grown Lobelia cardinalis before so when I saw that Wagler’s Greenhouse had a lot of them in the spring of 2017, I decided to bring three home. I had always wanted to try them because of their red flowers and the hummingbirds like them. I planted these three plants on the east side of the steps on the north side of the house. Here they would get plenty of sun, especially in the morning.
After I finished rejuvenating the bed on the south side of the house, I decided to purchase three more Lobelia cardinalis for that bed, too.
One afternoon I noticed one of the Lobelia by the porch looked as if it has been scalded. Maybe it was still wet from watering the evening before when the sun came out the next morning… I am not sure, but it was unusual.
One of the plants on the south side had the same issue…
The Lobelia cardinalis on the north side were looking pretty good after a few days.
While I was taking photos, I noticed the Lobelia on the south side looked a little strange…
Upon closer examination, I found an infestation. I am not one to do a lot of spraying, so I promptly pulled up these plants and put them in the burn barrel. So, that was the end of the Lobelia in the south bed…
I went out to Wagler’s and told her what happened. She said she noticed the problem and discarded their plants, too. It seems the other local greenhouses had more insect problems than usual in 2017, too. I brought home whiteflies from Mast’s Greenhouse on the tomatoes… When you are out plant shopping and see a problem, never hesitate to tell the owner or employees about it. Sometimes they get busy and are unaware.
The Lobelia cardinalis next to the porch were looking really good but the one in the back grew a little slower. Something was a little weird…
Expecting red flowers and getting pink was a little disappointing. I am not into pink even though it seems I have my fair share. Some plants I like only come in pink so I have no choice. The tag just said “Lobelia cardinalis” and didn’t say anything about the color. I guess I really never paid much attention to the fact that Lobelia comes in more colors than just red. They can be red, pink, purple, or white.
The last one to flower was bright purple which was better than pink…
Lobelia cardinalis grow in swampy areas in the wild and prefer much more water that you can imagine. Mine were planted next to the porch where the Conoclinum coelestinum were which are drought tolerant. I always thought it was weird how they grew to over 36″ tall in the summer of 2017 and now I realize it was because I was giving the Lobelia water almost every day. Of course, the smartweed liked the extra water, too!
Origin: Much of North America and northern South America
Zones: USDA Zones 2a-9b (-50 to 25° F)
Size: 24-48” tall
Light: Full sun to part shade
Soil: Likes wet soil and shouldn’t be allowed to completely dry out.
Water: Likes an ample amount of water.
Mulching: Applying a layer of mulch will help prevent the soil from drying out. They also need winter mulch to prevent the roots from heaving.
So, what did I think about the Lobelia cardinalis? Well, to be quite honest, I was expecting something much different. I have been collecting seed and plant catalogs since 1981 and I was expecting a completely different look. Despite them being pink, the photos I have always seen in catalogs and online seemed, well, different than an up close and personal look.
These plants did not return the following spring.
Another thing you may want to consider is the other plants around your Lobelia cardinalis. Since they prefer wet soil, you need to plant them among plants that like the same treatment. I will tell you, mine didn’t get much special treatment except when their leaves would start drooping.
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