Oxygenating Plants for Garden Ponds
Oxygenating plants provide shelter for spawning fish and their fry, as well as releasing oxygen directly into the water in strong light. They also take up mineral salts from the water that would normally encourage the growth of algae. A dozen or so should be planted in a small container and allow one container to every 2m2 (22 ft2) in a small pool, but as the pool enlarges relatively fewer containers are needed; a pool of over 55m2 (586 ft2) would require twenty containers. If the plants become too prolific it is a simple matter to lift out a few containers to allow more space. The following is a selection of useful oxygenating plants.
Canadian Pond Weed; Water Thyme
This plant originates in North America and has dark green, small thyme-like leaves with fine serrations. It increases mainly by the slender and brittle stems rooting at each whorl of leaves. Provided it is pruned of all dead growth it should never die. Keep it in a container to prevent it spreading unduly. A callitrichoides is a finer and more delicate variety.
Forms dark green clumps and prefers to root in gravel, pebbles and stonework; it is best seen in. The new shoots send out light green buds on the ends of the stems, which are mossy in appearance and harbour many varieties of animal life.
Water Violet; Featherfoil
The plant has feathery bright green leaves under water; only the flower stem rises above the surface and bears pale lilac blooms. It should be planted separately with a piece of the creeping root attached. In autumn the plant forms winter buds that sink into the pool floor to reappear in the spring. The American form H. inflata has white flowers.
Lagarosiphon muscoides (L major; Elodeacrispa)
A very good oxygenator with curly leaves on long trailing stems.
The delicate feathery leaves are characteristic of this group of plants; most will grow under water and give good service as oxygenators. They are very decorative. A portion of the plant can be weighted and sunk into the pool, where it will quickly root and grow. M. alterniflorum, spicatum, and verticillatumare all good species to grow and are widely available.
This plant has long wiry stems with wavy-edged leaves of a shiny brown that give it the appearance of seaweed. It enhances the look of most ponds and is ideal in moving water; plant in clumps near the pump or at the base of a waterfall.
Rorippa nasturtium aquaticum
This plant grows wild in the Northern Hemisphere and is well known for its culinary uses. Plantdirectly into containers of fine soil in shallow water and trim it regularly to keep it looking neat. A good oxygenator.
An Australian plant of creeping habit that grows well either submerged or at the water margin. It has very fine stems and leaves with tiny flowers.