Cardinal flower (Lobelia cardinalis) care guide

Group
Plants
Other names
Cardinal flower, Scarlet lobelia, Lobelia fulgens, Lobelia cardinalis 'Mini'
Family
Campanulaceae (bellflower family)
Origin
North and Central America: south-eastern Canada through the eastern and south-western USA and Mexico to northern Colombia
Water
freshwater
Maximum size
30 cm
Temperature
15–26°C
pH
6–8
Hardness
3–18 dGH
Care level
beginner
Lighting
Low to medium light; CO2 not needed

Care

Cardinal flower is a North American bog and riverbank perennial grown in gardens for its spikes of scarlet flowers. Above water it can reach 1.2 m; underwater it stays far smaller, with rounded light green leaves on stems 10–30 cm tall, and it has long been used in Dutch-style "plant streets". Tropica rates it easy, with low light and CO2 needs and a medium growth rate. Plant several stems in a row or group in the midground. In open-topped tanks it will grow out of the water and flower, and it can also be planted in garden ponds. Tropica also sells 'Mini', a compact form with small green leaves that suits the foreground of small tanks. The plant contains toxic alkaloids (lobeline and others), so wash your hands after handling and keep trimmings away from pets and children. Water figures are our estimate, not from the sources. Sources: Tropica (tropica.com/en/plants); Wikipedia (en.wikipedia.org/wiki/Lobeliacardinalis); Wikipedia, List of freshwater aquarium plant species. Checked October 2026.

Breeding

Take top cuttings and replant them. Emersed plants also produce side rosettes that can be split off, and seed can be raised on damp compost.

Compatibility and tank mates

Firm leaves are left alone by most fish and invertebrates. It tolerates a wide temperature range and suits both cooler and tropical tanks.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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