Lobelia Cardinalis Gigantea

Quick facts

Identity

Also known as

Giant Cardinal Flower

Synonyms

Lobelia cardinalis 'Wavy'; Lobelia cardinalis 'Gigantea'

Environment

Freshwater

Native to

Eastern and central United States, southeastern Canada, Mexico, Central America

Habitat

Wet stream banks, ditches, marshes, swamps, and pond edges, usually growing emersed as a bog plant along moving or standing water

Sourcing

Aquacultured

Conservation

Not Evaluated

Care

Care level

Easy

Growth form

Stem

Max height

4 – 12 in (10 – 30 cm)

Spread

4 in (10 cm)

Growth rate

Slow

Placement

Foreground, Midground

Water

Temperature

64 – 79 °F (18 – 26 °C)

pH

6.0 – 7.5

GH

4 – 15 dGH

dKH

2 – 14 dKH

PAR

30 – 80 PAR

Flow

Low-Moderate

Light

Medium

CO₂

Beneficial

Planting

Substrate

Nutrient-rich preferred

Feeds from

Both

Fertilizer needs

Medium

Colors

Green, Red, Purple

Feeding & breeding

Propagation

Cuttings

Something wrong or missing? Submit a correction

Care guide

Overview

Grown from stock that colonizes marshy banks and slow waterways across North America, this larger-leaved cultivar keeps the species' dual habit of emersed and submerged growth. Dark green leaves with a faint purple underside lighten to pale green once submerged. Its dense, upright habit makes it a common choice for structured, Dutch-style layouts.

Care

A slow-growing stem plant that forms tidy, compact bushes rather than tall spindly stems, making it well suited to the foreground or midground of an aquascape. It tolerates a wide temperature range and adapts to both submersed and emersed cultivation, though the leaf shape changes noticeably between the two forms. Medium to high light gives the most compact growth and best coloration, but the plant survives without CO2 injection, only growing more slowly and with looser leaves under low light.

Planting & trimming

Plant individual stems or small groups directly into a nutrient-rich substrate, spacing them loosely so light reaches the lower leaves. Trim by topping the main shoot or cutting side shoots, then replant the cuttings to keep the group dense and encourage lateral branching. Shortening the interval between trims produces the tightly packed "plant street" effect favored in Dutch-style layouts.

Fertilizing

Root tabs pushed near the root mass support steady growth since this species draws nutrients through both roots and the water column. Regular liquid fertilizing with nitrate, phosphate and a full micronutrient mix, including iron, encourages fuller lateral branching. Pale or yellowing new leaves usually point to iron or micronutrient deficiency rather than a macro shortage.

Propagation

Propagate by cutting side shoots or topping stems and replanting the cuttings directly into the substrate, where they root readily. Division of an established clump is also possible. Seed propagation is used for the terrestrial/emersed form but is uncommon in aquarium culture.

Problems

Newly submerged emersed-grown specimens often drop or reabsorb their original leaves before pushing out narrower, lighter green underwater foliage, which can look like a setback but is a normal conversion process. Shading from faster-growing neighbours causes lower leaves to yellow and drop, so give it an open, well-lit spot. Root nodes along the stem tend to sprout white roots, which can be trimmed away for a tidier appearance.

Sources

1. Lobelia cardinalis care: light, CO2 and placement · TankBud
2. Lobelia cardinalis - Cardinal flower - Flowgrow Aquatic Plant Database
3. Lobelia cardinalis Wavy care: light, CO2 and placement · TankBud
4. Native Aquatic and Wetland Plants: Cardinal Flower, Lobelia cardinalis

More Stem plants

Alternanthera Amabilis TricolorAlternanthera Bettzickiana GreenAlternanthera Bettzickiana RedAlternanthera LilacinaAlternanthera Red Broad LeafAlternanthera Reineckii