Hydrilla verticillata: complete guide

Overview

Hydrilla verticillata, commonly known as Florida elodea, waterthyme, or hydrilla, is a submerged aquatic plant from the Hydrocharitaceae family. Originally from Poland to Asia, it is now widely distributed in tropical and temperate water systems worldwide.

Hydrilla verticillata is an extremely productive aquatic plant used in aquariums and water gardens, but also known as an invasive weed in some water systems. In temperate controlled water systems, however, it can be managed and makes an excellent aquatic plant.

Appearance and Growth

Hydrilla verticillata grows as a long, stemmy submerged plant with numerous small side shoots branching off. The stems are thin and delicate, with tiny narrow leaves arranged vertically around the stem in whorls. This characteristic leaf arrangement gives the plant its name "verticillata".

The leaves are small, linear, and bright green in color. The plant grows very rapidly under favorable conditions and can produce substantial biomass. While this can be problematic in some areas, in controlled water systems it is beneficial.

The plant can reproduce both through fragmentation and seed production, although seed production in temperate climates is unlikely.

Ideal Location

Hydrilla verticillata grows best in shallow to moderately deep waters 0.5 to 2 meters deep. The plant enjoys full sun to lightly shaded aquatic positions.

The plant can grow in outdoor ponds, but in temperate climates it is better to maintain it in aquariums or controlled water gardens. The plant tolerates water temperatures of approximately 15 to 30 degrees Celsius.

The plant grows best in nutrient-rich waters, so ensure adequate nitrogen and phosphorus content in the water.

Water Quality

Hydrilla verticillata grows best in clean water with good oxygen levels. The plant is particularly tolerant of various water conditions and can even survive in slightly polluted water.

A pH of approximately 6.5 to 7.5 is ideal. The plant prefers moderately hard water but can adapt to soft water if necessary.

The plant helps keep water clean by consuming many nutrients from the water, making it particularly useful in aquariums and water gardens.

Aquarium Care

In aquariums, Hydrilla verticillata is an excellent background plant. Plant seeds or use fragments from existing plants. The plant will quickly develop roots on the substrate and grow upward.

The plant does not require special lighting, but grows better under good light levels. A standard aquarium light is usually sufficient.

The plant can be trimmed by simply pinching off the tops, which stimulates the plant to produce more branches. Fragments can be planted as new plants.

Pond Care

In outdoor ponds, Hydrilla verticillata can grow extremely rapidly and potentially become overwhelming. To prevent this, it must be regularly trimmed and thinned.

However, the plant can be beneficial because it produces abundant oxygen and absorbs many nutrients from the water, helping keep the water clean.

In temperate climates, the plant dies back in winter. Protection may be needed to overwinter fragments for the next season.

Temperature Range

Hydrilla verticillata grows best at temperatures between 15 and 30 degrees Celsius. In tropical water systems, it can grow year-round. In temperate climates, it will die back in winter.

The plant can withstand brief freezing periods but usually dies back when water freezes.

Companion Aquatic Plants

Hydrilla verticillata combines well with other aquatic plants in aquariums:

• Ludwigia: red background plant
• Rotala: small red-tipped stems
• Cabomba: delicate feathery-leaved plant
• Anubias: large-leaved background plant
• Java fern: triangular-leaved plant

Together they form an attractive layered planting scheme.

Practical Considerations

Hydrilla verticillata is considered invasive in some areas due to its rapid growth. Ensure you restrict the plant to aquariums or controlled water gardens in temperate regions.

In outdoor ponds, it must be maintained regularly. No fragments should escape into natural waters.

Conclusion

Hydrilla verticillata is a fascinating aquatic plant for aquariums and water gardens. With its rapid growth and ability to keep water clean, it is a valuable plant for controlled water systems.

The plant is very easy to grow and add to aquariums. For those interested in aquatic plant cultivation, this is an excellent starter plant. Ensure you treat this plant responsibly and keep it confined to aquariums in temperate climates.