Propagating Hygrophila polysperma 'Sunset'
Propagate the pink-veined Sunset (Rosanervig) cultivar of Hygrophila polysperma by stem cuttings, with steps, care and an important US noxious-weed warning.
Overview
Hygrophila polysperma 'Sunset' (also sold as 'Rosanervig') is a variegated form of H. polysperma, a member of the family Acanthaceae native to Bangladesh, India, China and Malaysia. It is easy to grow and one of the most popular tropical aquarium stem plants, accepting diverse water parameters and developing pink or orange hues near the light. As a cultivar it is multiplied vegetatively, exactly like the parent species.
Propagation Method (Cuttings)
The parent species propagates readily from stem cuttings, produces excessive new shoots quickly, and even an isolated leaf will often root itself. The Sunset cultivar follows the same fast, cuttings-based pattern: top a stem, replant the cutting, and the base produces new shoots.
Step-by-Step
- Cut a healthy top section of 5–10 cm just below a leaf node.
- Strip the lowest leaves to expose clean nodes.
- Push the cutting into nutrient-rich substrate so the bare nodes are buried.
- Leave the base; it will quickly send out new shoots that can be split off later.
- Replant the new shoots once rooted to build a fuller background.
Conditions for Healthy Growth
Growth speeds up under strong lighting, with nutrient-rich substrate and supplemental CO2, though the plant tolerates low-tech tanks well. The variegated pink and cream veins become more pronounced near the light source. Commercially the species is often grown emersed and converts to its softer submersed form once planted underwater.
Trimming & Maintenance
This is a fast grower that needs regular pruning — roughly every week to ten days — to manage its rapid growth and harvest cuttings. Frequent topping keeps the variegated stems bushy and stops the plant from taking light and nutrients away from slower neighbours.
Common Challenges
The main challenge is over-vigour: left untrimmed it shades and outcompetes other plants. Loss of variegation or pale growth usually means the plant is too far from the light or short on nutrients. Reversion to plain green shoots can be pruned out to keep the colourful form dominant.