Description
Lobelia siphilitica, commonly known as Blue Cardinal Flower, is a hardy marginal pond plant prized for its rich blue flower spikes that appear from late summer into early autumn. The upright blooms rise above fresh green foliage, adding cool-toned colour and height to pond edges at a time when many plants are fading.
Perfect for shallow water or damp soil, this clump-forming perennial is well suited to pond margins, bog gardens, and naturalistic planting schemes. It pairs well with other late-season plants, helping to extend interest and create a balanced display of colour.
Reliable and easy to grow in UK conditions, Lobelia siphilitica thrives in moist, fertile soil and a sunny to partially shaded position.
Key Features:
• Striking blue flower spikes in late summer
• Ideal for pond margins and boggy areas
• Adds height and late-season colour
• Attractive to bees and pollinators
• Height: approx. 60–90cm
• Planting depth: 0–10cm or moist soil
• Position: Full sun to partial shade
A great choice for bringing cooler tones and structure to your pond planting scheme later in the season.