Cardinal Flower Growing Requirements and CareCardinal Flowers should be spaced 1-2′ apart. I typically go ‘closer’ to reduce the number of weeds that pop up, since that will remove more sunlight/real estate. They can be in full sun to partial shade, but might require watering in full sun. I’ve not seen any pest problems or disease on any that I have grown. Cardinal Flowers grow well in partial shade with moist soil, as this is how you will find them in the wild. Typically along stream banks. In a flower bed it will require a bit of maintenance, but it can easily be done by following two main rules.
- Never let the soil dry out completely (remember, they grow along stream banks!)
- Never let the basal rosette of leaves at the base dry out completely
- The basal rosette will stay green all winter long. If it gets covered up, the plant will die. Remember the ‘growing along stream’ thing? Well, that matters a lot for this plant, as rising waters will remove any debris on the basal rosette, or at least remove enough leaves, etc.
Pest ProblemsI’ve not had any issues with wildlife eating this plant. I often need to protect certain species from rabbits/deer – but I’ve never seen any damage on any of my Lobelia species. So that is another large benefit of this plant in the garden. Be sure to scroll to the bottom of this article for our reference table on this plant. As it summarizes all the necessary grow/care info into one convenient source.
How to Grow Cardinal Flower from seedGrowing Cardinal Flower from seed is pretty easy, and economical. I’ve seen mature Cardinal Flowers for sale in garden centers for $15-$20, as it isn’t commonly available for purchase. I’ve never seen it for sale in big box stores. Well, I will tell you how you can get dozens of these beautiful perennials for about $2.50 (standard price for pack of seed). Just direct sow / sprinkle some seeds on top of the soil, and keep moist. The seeds of this plant are incredibly tiny. They are so small it is almost like powder, so be careful not to sneeze when planting or you might blow all your seed away! Most of what you read state that you should cold/moist stratify these seeds, or winter sow them. Since I like to experiment, I’ve tried growing without stratification, and have always had success. So it is up to you. If you are reading this in the winter, then go ahead and winter sow them in pots and protect them. There is no harm in doing so, and you will have mature plants sooner. When I sow them in pots the biggest issue I have that is unique to this species is thinning. Since the seed is so small I usually end up getting out the tweezers to remove unwanted seedlings a couple times. Once the basal rosette of leaves gets to be about 1″ diameter, I will plant out into the garden.
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How long from seed to bloom?How long does it take to get a flower? Well that will depend on how early you start your seeds, and ultimately how early you transplant out into the garden. Most of the time I will get blooms on Blue Lobelia flowers (albeit smaller stalks). But for Cardinal Flower I’ve gotten blooms the first year a few times. Mainly when I had the flowers transplanted into the flower bed by late June (also, I’m in zone 6).
Harvesting Lobelia SeedWhen saving seed from Cardinal Flower, or really any Lobelia you need to follow many of the same principles as other species. Let the seed pods dry out on the stalk until they are brown/dry before collecting them. If you collect the pods too early the seeds may not have developed fully, and therefore may not be viable to germinate.
Common Uses of Lobelia CardinalisThis plant prefers medium to wet soil, so this is a perfect plant for a rain garden. I generally grow them in my flower beds and just ensure that they are watered when necessary. As long as they don’t dry out, the plant will be fine in full sun, as I’ve only had them in full sun locations at my homes. They can make a wonderful border in a garden or along a fence, or a nice grouping to attract more hummingbirds. This plant can also be used in a micro-prairie, assuming the soil doesn’t get too dry. I plant on adding 6-12 of these to our micro prairie this year. I will keep an eye on them to make sure they get enough moisture. Check out our article on starting a micro prairie here. In fact, if you are in the process of making a butterfly or hummingbird garden, then this plant must be on your list. And remember, the more the merrier. More Cardinal Flowers should equal more hummingbirds. One single specimen will provide some food, but if you want to have hummingbirds frequently visit then you should consider many, many more. Since the spacing on this plant is so small you can really pack them in. I generally will try for about a dozen in a single bed, just to make sure my red blooms ‘advertise’ food to the hummingbirds. Mixing this plant with the Blue Lobelia is always a great idea, as they are similar but their bloom times often overlap, which gives you longer bloom duration for that section of your perennial garden. I’ve added some pictures below of how I’ve used Cardinal Flower in my gardens over the years. I hope you enjoy them!
Companion Plants for Cardinal FlowerA few species of plants that seem to do well with Cardinal Flower include the Great Blue Lobelia, Purple Coneflower, Blazing Star, and most varieties of Black-Eyed Susan (Rudbeckia). Just make sure you ‘protect’ the Cardinal Flower from encroachment. I have seen these species push right through other foliage, but it is best if they have their own small space. If you’ve enjoyed this article, please check out our other posts on Native Plants & follow us on Pinterest & Instagram. Don’t forget to subscribe to get our new content sent to you!
Cardinal Flower Facts & Reference Table
|Common Name||Cardinal Flower, Cardinal Plant, Red Cardinal Flower|
|Scientific name||Lobelia cardinalis|
|Bloom Time||Late Summer – July / August|
|Bloom Duration||Approximately 4 weeks|
|Bloom Size||Tubular flowers approximately 1/2″ diameter by 1″ long|
|Characteristics||Single or multiple stalks containing many flowers|
|Height||3-4′ (1-1.3 m)|
|Spacing/Spread||1-2′ (30-60 cm)|
|Light Requirements||Typically partial shade, but can tolerate full sun (will need water)|
|Soil Types||Varied – medium loam to clay.|
|Moisture||Medium to Wet – mustn’t dry out completely|
|Maintenance||Medium. Basal rosette of leaves at the base mustn’t get covered by mulch. Must have moist soil (watering).|
|Typical Use||Rain garden, border, wet meadow, or flower bed|
|Fauna Associations||Hummingbirds, Swallowtail butterflies, bumble bees|
|Stratification||Officially- 60 days cold moist stratification. But I never bother with this, and they germinate for me.|
|Native Range||All of North America Except Western half of Canada, and OR,WA,SD,ND,WY,ID,MT|
|Notes||This flower is absolutely beautiful. You could win awards with a strong display.|
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