Lobelia cardinalis

Species description

Care, breeding and tankmates

Plant profile

Placement

Foreground

It is best positioned in the midground of the aquarium, where its striking light green color can stand out. Planting it in a terraced 'street' formation is a classic Dutch aquascaping technique. It can also be used in the foreground of larger aquariums.

Botanical form

Stem

Underwater, Lobelia cardinalis features light green, slightly rounded leaves on thick, fleshy stems. Emersed, the leaves turn purple and it can produce brilliant red flowers. The submerged form is remarkably compact and neat.

Growth

Slow

This is a notably slow-growing stem plant, which significantly reduces maintenance requirements. CO2 injection is not strictly necessary but will promote fuller leaves and slightly faster growth. Its slow pace makes it ideal for highly structured layouts.

Substrate

High

Lobelia cardinalis is an exceptionally heavy root feeder that requires a highly fertile, deeply layered substrate to sustain its thick stems and large foliage. It flourishes in premium, nutrient-packed aquatic soils that can accommodate its massive, vigorous root system. Providing a substrate depth of 3 to 4 inches ensures the roots have ample space to spread and deeply anchor the rather buoyant plant. Without a constant, substrate-derived supply of macronutrients, the plant's lower leaves will quickly deteriorate, and its overall growth will stunt.

Column fertilization

Recommended

A consistent, moderate liquid fertilizer routine is beneficial for its long-term health. Because it grows slowly, over-fertilizing the water column can lead to algae settling on its broad leaves. Focus on a balanced supply of micro and macronutrients.

Root fertilization

Required

A rich substrate is highly advantageous for this species. It develops a substantial root system that heavily draws from soil nutrients. The use of root tabs will result in thicker, more robust stems and larger leaves.

Trimming

Occasional

To maintain a dense stand or 'street', trim the tops of the stems. The bottom portions will readily sprout new side shoots. The cut tops can be replanted right next to the original stems to thicken the grouping.

Propagation

Cuttings

Propagation is very easy by taking top cuttings and replanting them. Additionally, the plant naturally produces many lateral shoots which can be carefully detached and planted. The original cut stem will quickly form multiple new crowns.

Sensitivity

Moderate

Lobelia cardinalis is generally quite hardy and adaptable to various water parameters. Its main vulnerability is algae growth on its slow-growing leaves if lighting is excessive and nutrients are imbalanced. Ensure good water circulation around its dense base.

Layout role

Foreground, Midground, group

It is the quintessential midground 'street' plant in Dutch aquascaping. Its unique light green hue and fleshy texture offer brilliant contrast to fine-leaved or red background plants. Its structured growth habit provides a sense of order to the aquascape.