Lobelia siphilitica, hellblau

Upright, clump-forming perennial. Typically reaches a height of 0.6 - 1.2 m (2-4 ft) and spreads about 0.3 - 0.6 m (1-2 ft) wide.

Deciduous, ovate to lance-shaped, medium green, often with finely toothed margins. They form a basal rosette and are arranged alternately along the sturdy stems.

Dense, terminal spikes of numerous two-lipped, tubular flowers in shades of light blue to sky blue. Blooms appear from late summer to early autumn (August to October), providing late-season color.

Thrives in full sun to partial shade. Prefers partial shade in hotter climates or if soil moisture isn't consistently high.

Very good frost hardiness (USDA Zones 4-8).

Prefers rich, moist to wet, well-drained loamy or clay soils. It naturally grows in boggy areas, stream banks, and moist woodlands. It tolerates constantly moist conditions but can struggle in dry soils.

Ideal for bog gardens, rain gardens, pond edges, moist perennial borders, and naturalized areas. Its vertical flower spikes create a dramatic effect. Attracts hummingbirds, butterflies, and other pollinators.

High water requirement. Needs consistently moist to wet soil. Do not allow the soil to dry out, especially during blooming.

Generally low maintenance. Deadhead spent flower spikes to prevent excessive self-seeding (it can self-seed freely in ideal conditions) and promote a tidier appearance. Cut back stems after flowering or leave them for winter interest. Can be short-lived but often self-seeds to maintain colonies.

Containerized plants can be planted from spring to early autumn, allowing time for establishment before winter.