Great Blue Lobelia

Photo Credit: Andrew C

Long-blooming great blue lobelia (Lobelia siphilitica) stands out in summer. Dense spires of blooms float above long, pointed leaves. They’ll add a unique and vibrant violet-blue to any rain garden.

Preferring moist to wet soils, this native water-loving plant will thrive in a rain garden with occasional flooding. During extreme drought conditions, it may require extra watering. It grows well in sun and part shade.

Although short-lived, this clumping plant spreads easily by seed or underground roots known as rhizomes. If clumps are getting too big, they’re easy to split and make a great gift to share with neighbours. Plant with other rain garden favourites such as swamp milkweed, white turtlehead, or fox sedge.

Looking closely at the flowers reveals a tubular two-lipped structure that attracts bumble bees, long-tonged bees, butterflies, and hummingbirds who can reach the nectar hidden within. They transfer pollen from flower to flower. Small sweat bees can sometimes sneak in to snatch up pollen without dusting themselves, so you can’t count on them to help pollinate, but they are fun to watch.

Great blue lobelia is juglone tolerant, so no need to worry if you have a black walnut growing nearby. But plant away from hard surfaces where salt is applied in the winter.

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