Lobelia Cardinalis, commonly called the Cardinal Plant, is a North American native stem plant valued in the aquarium hobby for its rounded, glossy leaves that shift from green to red-purple under strong light. It adapts well to fully submerged aquariums, paludariums, and emersed terrarium setups, making it an easy, flexible midground plant for aquascapers at any experience level. This UNS tissue culture cup is grown pest- and algae-free, so it's ready to rinse and plant straight into your substrate.
Plant Profile
In the wild, Lobelia cardinalis grows along streambanks and wetland edges across eastern North America, where its emersed form produces the bright red flowers that give the plant its common name. In the aquarium it's grown almost entirely in its submerged leaf form — a compact stem plant that stays green under low-to-moderate light and takes on red-purple tones as light and nutrients increase.
Care & Planting Guide
Rinse the tissue culture gel from the roots before planting — run the cup under water or soak it and gently squeeze the gel free. Plant individual stems into a nutrient-rich substrate, spacing them to leave room to bush out. Trim the tops periodically and replant the cuttings to keep growth dense and compact rather than leggy. Lobelia cardinalis will grow without CO2, but supplementing it, along with iron and micronutrient dosing, noticeably deepens the red coloration and keeps the plant more compact.
A note on appearance: Many stem plants, including this one, are grown in their above-water (emersed) form, and the photo may not reflect how it looks once fully adjusted to life underwater. Leaf shape and coloration commonly shift as the plant transitions to submersed growth — don't be surprised if new growth looks different from what arrived in your order. Give it a few weeks to acclimate before judging its final look.
Quick Facts
| Common Name |
Lobelia Cardinalis (Cardinal Plant) |
| Scientific Name |
Lobelia cardinalis |
| Family |
Lobeliaceae |
| Type |
Stem |
| Skill Level |
Easy |
| CO2 |
Optional — not required, but strongly improves color and compactness |
| Requires Aqua Soil |
Beneficial — nutrient-rich substrate improves growth and color |
| Light Level |
Medium (40–80 PAR) |
| Max Height |
Up to 12" untrimmed; maintain shorter with regular trimming |
| Placement |
Midground |
| Growth Rate |
Moderate |
| Water Parameters |
pH 6.0–7.5 | 68–82°F |
| Propagation |
Cut the stem below a node and replant; also spreads via lateral shoots |
| Origin |
Eastern North America |
| Other |
Sold as tissue culture — pest-free and algae-free; rinse gel before planting |
FAQ
Does Lobelia Cardinalis need CO2?
No. It grows without it, but CO2 injection and strong lighting bring out the red coloration and keep the plant more compact.
How big does it get?
Up to about 12 inches if left untrimmed; regular trimming keeps it a dense midground plant closer to 4–6 inches.
Can it grow emersed or in a paludarium?
Yes. Lobelia cardinalis does well emersed and will even flower with its true red blooms above the waterline.
