About the species

Hygrophila costata is a South American stem plant with long, narrow leaves set closely along the stem. The stems can grow 25–60 centimetres long and the leaves up to ten centimetres. Plants on sale are usually grown above the water and then have rounder leaves with wider gaps; submerged they narrow and sit much closer together. Until recently the species was called Hygrophila corymbosa 'Angustifolia'.

Facts

• Latin name: Hygrophila costata
• Plant type: Stem plant
• Origin: South America
• Height: 20–30 cm
• Growth rate: Fast
• Position: Background

Light requirement

Medium light requirement. Reckon on around 0.5 W per litre or a modern mid-range LED unit. Too little light gives sparse, stretched shoots and pale leaves, while the right amount keeps the plant compact and richly coloured.

CO₂ & nutrition

Manages entirely without added CO₂, which makes it as suitable for a simple aquarium as for an aquascape. Liquid carbon or injected CO₂ speeds up growth but is never a requirement. Dose an all-round fertiliser with iron and micronutrients every week.

Planting

Split the bunch and set the stems one by one, about two centimetres into the substrate and two to three centimetres apart. Removing the lowest leaves first stops them rotting in the substrate. A group of five to ten stems looks far better straight away than single plants.

Carefully remove the pot and rinse the rock wool off the roots before planting — leftover rock wool can otherwise hinder rooting.

Care & propagation

Top the plant when it reaches the height you want and replant the cuttings — that propagates it and gives a denser group at the same time. Trim regularly so light reaches the lower leaves, and discard the old lower sections once they start thinning out.

Position in the aquarium

Given its mature height it belongs at the back or along the sides, where it forms a dense wall of greenery and hides equipment. In a smaller aquarium it can also be used as a solitaire in one corner.

Difficulty level

🟡 Moderate — wants stable lighting and regular fertilisation to look its best.

Delivery format

Delivered as a pot grown submerged, with the roots in rock wool. The pot holds several plants or stems that can be divided and planted separately.

Recommendation

A vigorous background plant for larger aquariums, at its best as a group along the back wall. Do not be surprised if the first new leaves look different from the ones you bought — that is the switch from air to water showing.