Wild Flowers: Great Blue Lobelia

Updated on March 31, 2016
OldRoses profile image

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been a volunteer at Rutgers Gardens for over a decade.


I was introduced to the Great Blue Lobelia when it popped up unexpectedly in my garden. I'm not sure how it got there. My guess would be it was courtesy of the birds who tend to excrete seeds all over my yard. But however it got there, I have enjoyed its beautiful blue flowers.

It is often called the Blue Cardinal Flower and it is, in fact, related to the well-known red Cardinal Flower. They are both Lobelia. The Cardinal Flower is Lobelia cardinalis while the blue cardinal flower is Lobelia siphilitica. It was named that because it was mistakenly thought to be a cure for syphilis. The Native Americans used it medicinally like aspirin to relieve aches and pains.

Where does it grow?

The Great Blue Lobelia is native to North America. It is hardy in zones 4 through 8. It prefers moist soil and semi-shade, often found along the sides of streams or in moist woodlands. The plants are short-lived perennials, lasting just a few years, however they will readily reseed themselves in your garden. They do not become a nuisance which is a good thing because the plants are quite large, growing between 2 and 3 feet tall. You can pinch back the plants to make them bushier.

The tubular blue flowers appear in late summer through early fall, August to October. They attract butterflies and hummingbirds. They do not attract deer! The Great Blue Lobelia is deer resistant, a real plus in areas like mine that suffer from an over-population of deer.

How do I make more of them?

The plants can be propagated in different ways. You can divide your plants in the fall. The plants stay healthier if they are divided every 2 to 3 years. Over-crowding causes them to grow poorly and encourages disease. It's easy to divide them. New plants develop in the form of leafy rosettes on the sides of the parent plants. Just break off those rosettes and plant them in a new location.

You can make cuttings in mid-summer. After the cuttings have developed roots, you can set them outside in your garden to get a start in settling into their new homes before winter.

Growing from seed is easy. You can either direct sow your seeds in the spring after all danger of frost or start them indoors 8 weeks before your last frost. Surface sow. The seeds need light to germinate. Germination will occur in 14 to 30 days. You can plant your seedlings outdoors after all danger of frost.

Allowing your plants to self-sow is the easiest way to create new plants. Instead of deadheading the flowers to make the plants appear neater, allow some to go to seed. In the spring, you will rewarded with seedlings. After a few years, you will have a whole clump of Great Blue Lobelia adorning your garden.

Questions & Answers

    © 2016 Caren White


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      • OldRoses profile image

        Caren White 2 years ago from Franklin Park, NJ

        You're quite welcome Flourish! I've owned 2 homes, both of which had shady yards so I've become rather knowledgeable about shade gardening.

      • FlourishAnyway profile image

        FlourishAnyway 2 years ago from USA

        Finding shade loving flowers has been a challenge for me so thank you!