Plants for pools

Aquatic plants not only add to the beauty of a pond, they are also essential for its well-being. Submerged, oxygenating plants revitalize the water and the floating leaves of sun-lovers like water lilies shade part of the surface and discourage the rapid build-up of algae. The roots of aquatic plants are also great for removing minerals on which the algae feed.

Aponogeton distachyos ( Water hawthorn)

The long, oval, floating leaves of water hawthorn make a change from the rounded pads of lilies. White, fragrant, hawthorn-like flowers with purple-brown anthers open in spring and autumn and are held just above the water on forked branches.

Divide the rhizomes of mature plants when dormant and repot into aquatic baskets. Roots must be 30-90cm (1-3ft) deep.


Ceratophyllum demersum ( Hornwort )

The slender stems of this useful oxygenator are clothed with whorls of dine, forked leaves, giving an overall feathery appearance. Few roots are produced, though the stems sometimes root into the mud at the bottom of the pond. Stems tips form into resting buds and sink for winter, drifting back up in spring. Propagate simply by pulling away some stem and floating it in water. Grows in water 60-90cm (2-3ft) deep.


Eichhornia crassipes ( water hyacinth )

It is hard to think that such an exotic aquatic has become a weed of tropical waterways worldwide. The inflated leaf stalks allow the water hyacinth to float, while dark, purplish roots hang down into the water. In hot summers, stalks of pale blue flowers marked with yellow and purple are produced. Lift and overwinter on trays of moist, soilless compost at a mnimum temperature of 13C (55F).


Hottonia palustris ( water violet )

As the water warms up in early spring, growth rises to the pond surface. Long stems bear deeply divided foliage above and below water. Stems of pale pinkish-lilac flowers are borne in spring. Plant in the muddy bottom of still, preferably slightly acid, shallow water, to 45cm(18in)deep.

Propagate by stem cuttings in spring and summer.


Hydrocharis morsus-ranae ( Frogbit )

Running stems produce new plantlets, so frogbit soon spreads to cover an area of water with its floating leaves like tiny, kidney-shaped lily pads. Small, papery, white flowers with yellow centres appear in summer. The plants are mostly free-floating, but will root into shallow mud, sinking to overwinter as buds.

To propagate, cut plantlets away from the parents. Needs a water depth up to 30cm (12in).