Great blue lobelia always amazes me when I see it. This summer (2010) I have seen growing wild in many different areas. I seen it in full sun and full shade, the soil has always been moist or relatively so. The plant holds its own next to other tall plants. This summer I spotted a clump of it with very dark blue flowers, really outstanding. Many people look for a true blue during the summer months and this is a wonderful plant that provides the color and fills a niche in the environment.
The plant starts out in the spring as a basal rosette. Meaning that it is a cluster of leaves that lies against the ground. Later in the season stems appear and usually at the end of July into August and September it flowers. The flowers are a true blue but varying shades of blue on different plants. The flowers are tubular in shape with 2 petals above and 3 below the center. It is very similar to red cardinal flower. Hummingbirds and butterflies are attracted to it too.
Great blue lobelia really adds great color to the garden and grows in sun, shade and semi shade. The soil should be moist or wet. Use it for the great blue color and in a pollinator garden. The bloom time makes it a great companion for red cardinal flower, green coneflower, goldenrod, wild bergamot, grasses, royal fern, turks cap lily, swamp milkweed and tall meadow rue.
Great blue lobelia can be divided in the spring or fall. We prefer to propagated it from seed. We recommend that you do not cut back seed head in the fall or if you do that you sprinkle the seed in areas that you would like the plant to fill in. If you get too many plants it is easily pulled in the spring. We start our seed in January in clear plastic boxes. We leave them outside until late March. They are them brought indoors and place on our light stands until that get their true leaves. We have found this increases survival rates. If the seedlings dry out at all they will parish.
Lobelia siphilitica - Great blue lobelia
Number of plants
-Provides great summer color
-Blue flowers vary in color
-Hummingbirds and butterflies use plant for nectar
-Height: 3 to 3 Feet
-Zone: 3 to 9