Featured Flower: Great Blue Lobelia

In the gardening world we all have our colours – the hues that draw us in and inspire us. For me, the flower colours that I love the most are shades of pink, purple and blue. And although I appreciate all of the other colours, and love the combinations that can be created when planting contrasting colours together, these are the shades that I always go back to. And so it is no surprise to me that I absolutely love Great Blue Lobelia, Lobelia siphilitica, with its tall spikes of soft blue flowers.

Lobelia siphilitica is native to Eastern parts of Canada and the United States. It is relatively low maintenance and can grow in sun to shade provided that it is in moist to wet soil. This plant, like it’s relative the Cardinal Flower (Lobelia cardinalis), is a moisture lover and will not tolerate dry soil or drought of any kind. (To read more about the Cardinal flower see my Feature Flower post on it here: https://doctorb.blog/2019/07/26/featured-flower-the-cardinal-flower/). The height of Great Blue Lobelia is somewhat variable depending on the conditions that it is in, but typically grows up to 1 meter (2-3 feet), with the spikes of flowers being taller than the leaves. The flower itself has an upper lip consisting of 2 segments that fold backwards, and a lower lip of 3 larger segments. The tubular shape make this flower more appropriate for bumblebees, species of long-tongued bees, hummingbirds and large butterflies. The flowers will appear late in summer and last into early fall, adding a nice pop of colour to a perennial garden in the dwindling days of summer. As the plant forms into large clumps it can be easily divided in the spring for planting elsewhere in the garden or sharing with friends. I do not recommend ingesting any of this plant, in fact it does contain toxins that can make you sick if consumed in large quantities. However the Latin name siphilitica comes from the fact that it historically was believed to be a cure for syphilis.

I have planted two Great Blue Lobelias in the pollinator garden at the school. I chose this plant in particular because of its happiness in shade and because of the bloom time – I want the garden full of colour when the students return for a new school year. I did not factor in the need for moist soil, which is generally lacking in the school garden. But I am careful to water it every day when I visit – it gets top priority in the water allotment. And I am happy to report that it is thriving and has even begun to bloom! Next year I plan to incorporate it into my own perennial garden where I think it will look lovely next to some shade-tolerant goldenrod.

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