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Cardinal Flower
Lobelia cardinalis
Cardinal Flower blooms from July through September.
Mature size, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not.
Growing Cardinal Flower
Plant it in part sun. It prefers high water. It is hardy in USDA zones 3–9. Expect it to reach about 3.3 ft tall and 1.3 ft wide at maturity, in roughly 2 years.
When to plant Cardinal Flower
Plant Cardinal Flower in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. For the middle of its hardy zones 3 to 9 range, spring means March to May and fall means August or September. Once settled, it blooms from July to September.
Month-by-month timing for your zone is on the planting calendar: for the middle of its range, start with zone 6 in March.
Good to know about Cardinal Flower
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
All parts are poisonous if eaten, from flowers to roots, holding lobeline-type alkaloids. Toxic to people, dogs, cats and horses; large amounts can be dangerous. per ASPCA and NC State
Worth knowing
The scarlet, nectar-rich tubular flowers depend on hummingbirds to pollinate them: insects struggle to navigate the long tube. Its late bloom fuels southbound migrating hummingbirds. per USDA and University of Illinois
How tall it gets
In average ground it stays 2 to 4 ft, but rich, constantly wet soil pushes the flower spikes to 5 or 6 ft. Plan spacing for your site. per NC State and Penn State
Keep the soil wet
It needs rich, constantly moist to wet soil and must never dry out: a streambank, pond edge, or rain garden suits it well. Drought kills it. per NC State
Deer and rabbit resistant
Deer and rabbits leave it alone, so it can persist even where browsing is heavy. The same toxic alkaloids that poison make browsers avoid it. per Wisconsin
Short-lived; renew it
It is a short-lived perennial. To keep a stand going, let some seed drop (the tiny seed needs light, so don't bury it) and divide the rosettes. per Wisconsin
Nicknamed Indian tobacco
Its main alkaloid, lobeline, acts on the same nicotine receptors tobacco does, so Lobelia earned the name Indian tobacco and was once used as an emetic. per Molecules
What pairs well with Cardinal Flower
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
English Daisy
Takes full sun to part sun and moderate to high water; blooms in mid spring, before this one opens; low at 6 in, to carpet the ground beneath; both offer pollinator forage, in different months.
Jacob's Ladder
Takes part sun to part shade and moderate to high water; blooms in late spring, before this one opens; both are strong pollinator plants, and they feed in different months; lower at 1.6 ft, for the front of the border.
Aster
Takes full sun to part sun and moderate to high water; overlaps, then carries the display into mid fall; both are strong pollinator plants; its seed heads stand through winter, for structure and the birds.
Pansy
Shares part sun and moderate to high water; blooms in early spring, before this one opens; lower at 8 in, for the front of the border; both offer pollinator forage, in different months.
Chives
Takes full sun to part sun and moderate to high water; blooms in late spring, before this one opens; both are strong pollinator plants, and they feed in different months; lower at 12 in, for the front of the border.
Sweet Alyssum
Takes full sun to part sun and moderate to high water; low at 5 in, to carpet the ground beneath; overlaps, then carries the display into mid fall; both are strong pollinator plants.
Autumn Crocus
Takes full sun to part sun and moderate to high water; overlaps, then carries the display into mid fall; low at 6 in, to carpet the ground beneath; both offer pollinator forage.
Hyacinth
Takes full sun to part sun and moderate to high water; blooms in early spring, before this one opens; lower at 10 in, for the front of the border; both offer pollinator forage, in different months.
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