Lobelia Cardinalis

Plant Overview

Lobelia cardinalis is a stunning amphibious plant native to North America, prized in the aquarium hobby for its distinctive spoon-shaped leaves and vivid two-tone coloration. A classic choice for midground placement, it adds bold structure and a splash of colour to any planted tank.

Quick Reference

Appearance

Lobelia cardinalis features broad, rounded leaves arranged alternately along sturdy stems. The topside of each leaf is a rich olive to bright green, while the underside reveals a striking violet-purple — a contrast that becomes more vivid under stronger lighting. Submerged growth is more compact and colourful than its emersed form, making it a rewarding plant to watch transform in the aquarium.

Care Guide

• Lighting: Medium to high light encourages compact growth and intensifies the purple underside. Low light results in leggy, pale stems.
• CO2: Not strictly required, but CO2 injection noticeably improves growth rate and leaf colour.
• Nutrients: Benefits from regular macro and micronutrient dosing. Iron supplementation enhances the purple pigmentation on leaf undersides.
• Maintenance: Trim the tops when stems grow tall and replant cuttings to maintain a dense, bushy midground cluster.

Aquascaping Uses

• A natural fit for the midground, providing bold leaf texture between fine-leaved foreground and background plants.
• Works beautifully in Nature Aquarium and Dutch-style layouts as a structural accent plant.
• The purple-green contrast pairs well with red stem plants and bright green carpeting species.
• Plant in groups of 5–9 stems for maximum visual impact.