Description of Lobelia cardinalis (Cardinal Flower)

Lobelia cardinalis is cardinal flower, known for tall spikes of scarlet blooms in late summer. It likes wet ground and brings colour when many bog plants are past their peak.

Appearance

It forms leafy clumps, then sends up upright stems with bright red flowers. In flower it often reaches 60 to 90cm. In good conditions it can bulk up into a strong colony.

Care Guide

Keep it damp and it performs. Let it dry and it fades fast.

Sun: Sun to part shade. In warmer spots, a little shade helps.
Soil: Fertile, moisture-holding soil.
Water: Constant moisture through summer. Avoid drying at the crown.
Feeding: A spring feed helps build stronger flower spikes.
After flowering: Cut stems back, or leave until late winter for structure.

It can be short-lived in dry summers, so allow a bit of self-seeding or divide in spring to keep it going.

Suitability for Bog Garden

This is a strong mid-back bog plant. Plant in groups for impact and pair with green foliage so the flowers pop.

It also works at the pond edge if the soil stays saturated, especially in a basket on a shelf.

FAQ

When does Lobelia cardinalis flower?
Late summer into early autumn in most UK gardens.

Does it need wet soil?
Yes. Constant moisture gives the best flowering and keeps foliage healthy.

Can it grow in shade?
It copes in part shade, but flowers best with more light.

Can I divide it?
Yes. Divide in spring as growth starts, or allow some self-seeding.