Propagating Ludwigia glandulosa 'Perennis' from Cuttings

How to propagate the bronze-maroon Ludwigia glandulosa 'Perennis' by stem cuttings, with the high light, CO2 and iron it needs to hold its rich red-purple colour.

Overview

Ludwigia glandulosa 'Perennis' is a selected line of L. glandulosa, an amphibious plant from the southeastern United States that can grow partially or fully submerged. The leaves turn red or purple under sufficient light and greener when light is insufficient, so this cultivar is grown for the deep red-purple narrow-leaf colour it shows in the mid-to-background of a planted tank.

Because 'Perennis' is a selected cultivar rather than a true species, it does not come true from seed in the aquarium. It is propagated vegetatively from cuttings, which keep the parent's narrow leaf shape and bronze-maroon colouring.

Propagation Method (Cuttings)

Stem plants are propagated by cutting off the top few centimetres of a stem and planting it directly into the substrate; new buds and roots grow from the internodes. Many stem plants only form more lateral buds once the apical tip has been cut, so topping the parent both gives you a cutting and encourages the base to branch and become bushier.

Step-by-Step

1. Choose a healthy upper stem and cut the top 5-10 cm with clean scissors.
2. Strip the lower leaves so a bare section of stem can be buried in the substrate.
3. Plant the cutting into the substrate; roots and buds will grow from the buried internodes.
4. Leave the parent base in place so it sends out side shoots and becomes bushier.
5. Mature side shoots can later be cut off and replanted once they are a few centimetres long.

Conditions for Healthy Growth

L. glandulosa requires warm temperatures and abundant light, and benefits significantly from phosphates and nitrates; CO2 supplementation is needed for optimal growth. Strong light is what drives the red-purple colour, while too little light reverts the foliage toward green. Provide ample iron and trace elements to sustain the colour as the cuttings establish.

Trimming & Maintenance

Aquatic stem plants take replanting well and regrow root systems quickly, so regular topping is the main maintenance task. Repeatedly cutting the tops keeps the group dense and produces a steady supply of cuttings; over time the tired lower stems can be discarded and freshly rooted tops replanted in their place.

Common Challenges

The main challenge is colour: without enough light, CO2 and iron the foliage drifts toward green and the cultivar loses its appeal. Submersed and emersed forms can also differ, since emersed (above-water) growth on Ludwigia tends to be stiffer and less richly coloured than the submerged form, so allow newly submerged cuttings time to convert.