Simple steps to successfully growing the Great Blue Lobelia
This list is the key requirements to growing the Great Blue Lobelia successfully;
- Full sun to Partial Shade
- Moist or wet soil
- Will tolerate many types of soil, even clay. Although probably not sand
- Needs at least 1′ (30 cm) diameter of ground space
- This plant is hardy in zones 4-8. Find your garden zone here.
General Description and Facts
The Great Blue Lobelia, Lobelia siphilitica, is a perennial flower native to most of North America. It will grow 2-3′ tall in optimum conditions producing several stalks or spikes of dark blue/violet flowers. So, it is erect in its footprint, and doesn’t branch out. The blooms are quite showy, and are mainly pollinated by bees. I’ve found this plant in partially shaded meadows along the Appalachian Trail near my home. The soil/area didn’t seem that moist, but obviously this plant was happy there! Based on that, I’ve added some plants to our backyard micro-prairie. See how to grow your own micro prairie here==>>How To Make Micro PrairieThe flowers are short tubes that will have two petals stick up, above the tube. And then 3 petals hanging down from the tube mouth, almost like 3 tongues hanging out. Based on my familiarity of this bloom I’ve identified several other ‘weedy’ Lobelia species around my home such as Indian Tobacco (Lobelia inflata). It always feels good to know that you can apply knowledge gained for one thing to something else!
Great Blue Lobelia Growing Requirements and Care
The Great Blue Lobelia doesn’t require much space, as it will send stalks vertically. Because of that, you can space them 1-2′ apart (30-60 cm). I prefer to pack them in tight, as this will keep weeds down since there will be less sunlight available to the bare patches. These plants will do best in partial shade with moist soil. I’ve personally grown them in full sun, and clay soil – but needed to water them occasionally.
How to Grow Blue Lobelia from seed
Purchase Seed
We have ordered a variety of native flower seeds from Everwilde Farms, which you can order right from Amazon through our link on our RECOMMENDED PRODUCTS PAGE. (We may earn a small commission when you purchase through our links, at no cost to you. This helps support our website.)
Does Blue Lobelia Seed need stratification?
I personally don’t stratify these seeds, and I always get plenty of germination. However, most references say it needs about two months of cold moist stratification. And since this seed is so tiny, it pretty much means you have to winter sow them. I believe that this seed would be too small to mix with vermiculite or sand, or even use a paper towel. But as I said – I just sow the seed in early May, and this works just fine for me. I always end up with a ridiculous number of seedlings, and have to thin/separate them with tweezers.When can I transplant Blue Lobelia into the garden?
The earliest I will transplant my seedlings is when the basal rosette of leaves are about 1″ in diameter, for the whole plant. At that point, the roots should be several inches deep, and the plant out to be large enough to survive just fine. The video below discusses the entire sowing process I use in detail;How long from seed to bloom for the Great Blue Lobelia?
How long does it take to get a flower when Blue Lobelia is grown from seed? Well that will depend on how early you start your seeds, and ultimately how early you transplant out into the garden. I’m in zone 6, and I usually get blooms on Blue Lobelia if I transplant by July. I also get blooms if I grow them in 4″x4″ pots. I’ve transplanted blooming Blue Lobelia flowers from pot into the garden as late as October. So, you should be able to get blooms the first year as long as you start early enough. That is just another benefit of this perennial.How and when to divide the Great Blue Lobelia?
Lobelias that are several years old, or well established can be divided in the spring. Do not divide this plant in the fall, as the roots are quite shallow, and might get pushed out of the ground due to frost. So, divide the offshoots from the main plant. Then plant the offshoots into a new location, and water. This root divisions don’t ‘store’ very well for Lobelia.How to save Lobelia Seed
The process for saving Blue Lobelia seed is the same as its cousin, the Cardinal Flower. 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. Store seed in zip-bags if truly dry, or keep in paper bag or envelope.
Common Uses of Blue Lobelia
Companion Plants for Blue Lobelia
The most obvious companion plant for Blue Lobelia would be its cousin, the Cardinal Flower. But other species that would do nice and not encroach or crowd out Blue Lobelia would be Purple Coneflower, Blazing Star, and most varieties of Black-Eyed Susan (Rudbeckia). Although you would probably have to keep an eye on the Rudbeckia to make sure it didn’t start new plants by going to seed next to Lobelia.Is the Blue Lobelia edible?
In a nutshell, no it isn’t. This plant is toxic, but from what I have read you need to consume a lot of it for it to be fatal. So don’t eat or consume it. Apparently various Native American tribes used this plant as a remedy to treat coughing, nosebleeds, and general colds. The Meskwaki even used the root as an ‘anti-divorce’ remedy. They would grind up the roots and feed them to the couple that was having problems [1]. I guess it is the power of suggestion or placebo effect…… If you’ve enjoyed this article, please check out our other posts on Native Plants. Don’t forget to subscribe to get our new content sent to you! PIN IT:
Blue Lobelia Facts & Reference Table
| Common Name | Blue Lobelia, Great Blue Lobelia, Blue Cardinal Flower |
| Scientific name | Lobelia siphilitica |
| USDA Zone | 4-9 |
| Bloom Time | Late Summer – July / August / September |
| Bloom Duration | Approximately 4-8 weeks |
| Color | Blue, Dark Blue, Violet-Blue |
| Bloom Size | Tubular flowers approximately 1/2″ diameter by 1″ long |
| Characteristics | Single or multiple stalks containing many flowers, Blooming top to bottom |
| Height | 2-3′ (0.5-1 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-loam. |
| Moisture | Medium to Wet – mustn’t dry out completely |
| Maintenance | Minimal, depending on conditions. |
| Typical Use | Rain garden, border, wet meadow, or flower bed |
| Fauna Associations | Bumblebees, and other bees. |
| Larval Host | None |
| Sowing Depth | Surface |
| Stratification | Officially- 60 days cold moist stratification. But I never bother with this, and they germinate for me. |
| Native Range | Eastern North America |
| Notes | This flower is beautiful. I would describe it is strong, ornate, structured. |
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