Propagating Hydrocharis morsus-ranae (European Frogbit) by Stolons

How to propagate floating European frogbit through daughter rosettes on stolons, with a strong warning never to release this North American invasive into the wild.

Overview

Hydrocharis morsus-ranae, European frogbit, is a free-floating flowering plant with circular floating leaves that have visible aerenchyma underneath and petioles 6-14 cm long. It grows as individual rosettes that the plant links together, ranging from 1 to 30 cm. Its small flowers carry three greenish-red sepals and white petals.

It is native to Europe and Asia, where it lives in slow-flowing rivers, stagnant waters, ditches and oxbow lakes, so it favours calm, still surfaces in the aquarium.

Propagation Method: Offsets on Stolons

European frogbit reproduces through stoloniferous growth, developing individual rosettes connected along the stolons. New daughter rosettes form along these runners, so the plant multiplies vegetatively into a connected colony. Propagation is simply separating the established daughter rosettes.

Step-by-Step

Let the parent rosette grow until it pushes out stolons bearing small daughter rosettes.
Wait until each daughter rosette has formed its own floating leaves.
Gently separate the daughter rosette from the connecting stolon.
Return the separated rosette to a calm patch of the surface so it can re-establish.
Lift connected colonies out in one piece when thinning.

Conditions for Healthy Growth

Placement: free-floating on a calm, still surface.
Temperature: 15-26 C; tolerant of cool to subtropical water.
pH 6.0-8.0, GH 4-18.
Lighting: medium light.
Avoid strong surface movement that wets the floating leaves.

Maintenance

Thin the colony regularly so it does not cover the whole surface and shade out plants below. Because connected rosettes form dense surface masses, scooping out clumps every couple of weeks keeps growth in check.

Common Challenges

The dominant challenge is its vigour: it readily forms dense masses on the surface. Controlling spread inside the tank and, above all, preventing any escape into the wild are the key concerns for this species.