Introducing the Enigmatic Lobelia Cardinalis Aquarium Plant

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Lobelia Cardinalis (cardinal flower) Care Guide - Planting, Growing, and Propagation - Submerged form

Lobelia cardinalis, with its captivating oval leaves when submerged and vibrant red flowers when emerged, is a truly mesmerizing green stem plant. In this article, we will explore the fascinating world of the dwarf version of Lobelia cardinalis, a submersed form known for its smaller size and compactness when grown under optimal conditions. Join us as we delve into the care and growth of this remarkable aquatic plant, particularly its use in Dutch-style aquariums.

Quick Facts about Lobelia Cardinalis var. mini

  • Common Name: Lobelia cardinalis
  • Other Names: Cardinal flower, Red Cardinal, Blood-red Lobelia, Purple Lobelia, Mexican Lobelia, Emersed Dwarf Lobelia Cardinalis, Lobelia cardinalis mini
  • Scientific Name: Lobelia cardinalis
  • Tank Size (minimum): 5 gallons (~20 liters)
  • Difficulty: Easy
  • Lighting: Moderate to high
  • Optimal pH: 6.0 – 7.5
  • Optimal hardness: Soft to moderately hard water (2 – 12)
  • Optimal temperature: 61 – 79 °F (16 – 26 °C)
  • Substrate: Any
  • Can float: No
  • Can Be Grown Emersed: Yes
  • Size: 4 – 8 inches (10 – 20 cm)
  • Growth Rate: Slow to moderate (submersed), moderate (emersed)
  • Placement in Tank: Foreground / midground
  • Fertilizer: Needed
  • CO2: Not needed but recommended when submersed
  • Propagation: Cutting, lateral shoots, and seed (emersed)

Did you know that Lobelia cardinalis held ceremonial and medicinal significance for Native American tribes? For example, the Iroquois used the cardinal flower to treat fever sores, cramps, and upset stomachs.

The Origin and Habitat of Lobelia Cardinalis

Lobelia cardinalis, also known as the cardinal flower, is a flowering plant belonging to the bellflower family Campanulaceae. Named after the Flemish botanist Matthias de L’Obel, Lobelia cardinalis was introduced to Europe in the 1620s and earned its common name due to its resemblance to the red robes worn by Roman Catholic cardinals.

This captivating species is native to the Americas, ranging from Canada and the United States to Mexico and Central America, extending all the way to Colombia. It thrives in humid areas such as streambanks, ponds, wet meadows, and marshes. To recreate its natural habitat, Lobelia cardinalis can be grown in aquariums, gardens, ponds, and streams with conditions resembling its native environment.

In its natural setting, Lobelia cardinalis flourishes in rich, medium to wet soil, basking in full sun to part shade. Its stunning red flowers bloom from late summer to mid-fall.

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A Closer Look at Lobelia Cardinalis

Lobelia cardinalis exhibits varying characteristics depending on its habitat and environmental conditions. Its emersed form appears drastically different from its submersed growth.

Emersed Form

Lobelia Cardinalis Care Guide - Planting, Growing, and Propagation - Emersed vs Submerged form

When grown emersed, Lobelia cardinalis can reach a towering height of 4 ft (1.2 meters). Above the water’s surface, it blossoms with scarlet flowers and develops captivating purple tints. Compared to its submerged form, its growth rate is significantly faster.

Emersed Lobelia cardinalis leaves exhibit a dark green hue with a purple underside, thriving in marshy nursery conditions. These toothed leaves, ranging from lanceolate to oval, can grow up to 8 inches long (20 cm) and 2 inches broad (5 cm). Their enchanting appearance makes them popular as both vase and garden flowers.

Submerged Form

In aquariums, Lobelia cardinalis takes on a completely different guise. Its leaves are much smaller, measuring between 0.5-0.7 inches (1.5 cm), and exude a lovely shade of light green, reminiscent of lush green grass. The veins of the leaves are clearly visible, giving the foliage a smooth and well-formed appearance without any distortion or discoloration.

It’s important to note that the purple color exhibited by Lobelia cardinalis only manifests when grown emersed. In the aquarium, the purple color will fade away, leaving behind a vibrant light green hue.

Lobelia cardinalis finds its home in Dutch aquascapes, particularly in the midground and foreground sections. When exposed to higher light levels, the plant assumes a bushy and compact appearance, while lower lighting results in sparser and more slender growth.

Setting the Perfect Stage for Lobelia Cardinalis

To achieve optimal growth and vibrant appearance, Lobelia cardinalis requires specific tank conditions and water parameters.

Tank Requirements and Water Conditions

Lobelia cardinalis can thrive in both emersed and submerged environments, making it a fantastic choice for garden ponds, terrariums, and paludarium setups. Whether you choose to grow it emerged or submerged, there are a few key factors to consider.

Tank size: While Lobelia cardinalis can adapt to various tank sizes, a minimum of 5 gallons (20 liters) is recommended for its growth.

Water type, temperature, hardness, and pH: The ideal temperature for Lobelia cardinalis is between 61 – 79 °F (16 – 26 °C). It can tolerate low temperatures down to 34 °F (1 °C).

Maintaining a pH level between 6.0 – 7.5 and moderately hard water (2 – 12 GH) is crucial for its thriving. Lobelia cardinalis does not tolerate high salinity levels, so it’s not suitable for brackish tanks.

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Lighting: Lobelia cardinalis thrives under well-lit conditions. Ample illumination is vital for its growth and appearance. Research shows that low light levels can significantly impact its growth rate and diminish its visual appeal. Aim for moderate to high lighting for optimal results.

Substrate: The root system of Lobelia cardinalis varies depending on its growth form. When grown emersed, it develops a robust root system that can extend up to 12 inches (30 cm) deep. In submerged conditions, its roots are shorter and less strong.

Nutrient-rich substrates, such as ADA Amazonia, are ideal for Lobelia cardinalis. However, with regular fertilization, the plant can thrive in any substrate.

CO2 and Fertilization: While CO2 supplementation is optional, providing Lobelia cardinalis with sufficient CO2 and essential nutrients will enhance its growth, leaf formation, and overall health. Liquid fertilizers are preferable to root tabs, as they promote a better growth rate. If you have shrimp in the tank, ensure that high CO2 and copper levels, often found in fertilizers, are not harmful to them.

Caring for Lobelia Cardinalis

Lobelia Cardinalis (cardinal flower) Care Guide - Planting, Growing, and Propagation

Lobelia cardinalis is an easy plant to care for, provided it receives the necessary maintenance and attention. Here are some key points to consider:

Pruning: Regularly trim overgrown and old leaves of Lobelia cardinalis using sharp trimming scissors. Removing lengthy stems not only maintains the plant’s aesthetic appeal but also promotes denser growth and lateral shoot development.

Planting and Propagation of Lobelia Cardinalis

Planting Lobelia cardinalis is a straightforward process. Place the specimens in a substrate with a thickness of 2 – 3 inches (5 – 7 cm) to facilitate rooting. Interestingly, dense groupings do not hinder Lobelia cardinalis, so there’s no need to space the plantlets too far apart.

After planting, dose the tank with plant fertilizers to stimulate new shoot formation and promote a healthy appearance. Lobelia cardinalis can be easily propagated through cutting mature stems, lateral shoots, dividing daughter plants from the parent plant, or even by seed when grown emersed. Keep in mind that its beautiful purple color is only achieved when grown emersed.

Common Challenges and Solutions

While Lobelia cardinalis is a resilient plant, it can face a few challenges under certain circumstances:

Diseases: Crown rot is a common condition that affects ornamental plants like Lobelia cardinalis. It causes the crown to wither, leading to overall decline. Regular observation and timely intervention can help address such diseases.

Discoloration and leggy growth: Yellow-tinted stems and leggy growth can occur due to inadequate lighting or nutrient levels. Trimming affected stems is recommended to maintain the plant’s health and appearance.

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Pests: Pest snails, particularly in outdoor ponds and gardens, can feast on the leaves and branches of Lobelia cardinalis. Regular monitoring and removal of snails, as well as plant disinfection, can help mitigate this problem.

Poor and slender growth: Inadequate CO2, low light, or low nutrient levels can lead to poor and slender growth. Adjusting these factors and providing proper nutrition will help the plants return to a healthy state.

Toxicity: Like many plants in the Lobelia genus, Lobelia cardinalis contains potentially toxic alkaloids, including lobelamine and lobeline. Ingesting large quantities can lead to various symptoms, including nausea, vomiting, diarrhea, and weakness. Handle with care and avoid consumption.

The Benefits of Lobelia Cardinalis

Lobelia cardinalis offers a range of benefits in the aquarium environment:

  • Aquascape: Lobelia cardinalis is a beautiful addition to Dutch-style aquascapes, adding vibrant colors and texture.
  • No overshadowing: It won’t overshadow other aquatic plants, making it a great choice for maintaining biodiversity in your tank.
  • Hiding place for fish, fry, and shrimp: It provides cover and shade for small fish, fry, and shrimp, creating a safe and secure environment.
  • Foraging place: Lobelia cardinalis hosts a buffet of biofilm, a perfect food source for newly hatched fry and shrimplets.
  • Oxygenation: As a growing plant, Lobelia cardinalis oxygenates and aerates the tank water, promoting a healthy aquatic environment.

Compatible Tankmates

Lobelia cardinalis is compatible with a wide variety of freshwater fish and invertebrates, making it a versatile addition to your tank. It can coexist with species such as Betta fish, swordtails, tetras, danios, platies, guppies, otocinclus catfish, and various shrimp species, including red cherry shrimp and amano shrimp.

Caution: Avoid keeping Lobelia cardinalis with crayfish, freshwater crabs, or aggressive fish species known for their plant-devouring habits, such as Texas cichlids, front cichlids, and Oscars.

Where to Buy Lobelia Cardinalis

Lobelia cardinalis is readily available at local fish stores and online aquarium stores. You can purchase a pot of Lobelia cardinalis for an affordable price, usually around $5. When selecting your plant, ensure it appears fresh and healthy, devoid of any signs of damage or poor health.

In Conclusion

Lobelia cardinalis is a masterpiece in the world of aquatic plants, perfect for embellishing the midground and foreground of freshwater aquariums. With its stunning appearance and easy care requirements, Lobelia cardinalis is an excellent choice for both beginners and experienced aquarists. Just remember to provide the ideal conditions of lighting, fertilization, and CO2 to witness this plant’s full potential in your aquatic haven. So, why not add a touch of elegance to your tank with the alluring Lobelia cardinalis?