Water in the garden – whether a formal pool, a small stream, a short cascade or a wildlife pond – will allow you to grow many plants that do not thrive in any other conditions. Even in the smallest plot you can have a trough with dwarf water lilies floating in it. In a larger garden a formal or informal pond can create a strong focus and set the garden’s style. It may incorporate a fountain or waterfall to create movement, sound and liveliness and water lilies will complete the scene.
Floating plants, marginal, deep water and bog plants all add to the interest of a water garden but need to be catered for carefully. Ponds should be made with shelves at different heights so that pond baskets can be put at the heights best suited to the various plants.
Marginal plants are, in the main, very attractive plants grown at the edges of pool in shallow water about 3-6 in deep, but sometimes up to 12 in deep. Some species, such as water mint (Mentha aquatica) and Veronica beccabunga, also help to oxygenate the water.
Ferns will grow well at the borders of informal pools and can form a good transition between a stream and the garden. Plants grown at pond margins also provide shelter for wildlife. Iris laevigata is tall and stately with fans of green sword-like leaves and lavender-blue flowers.
Butomus umbellatus has clusters of pale pink flowers in summer and early fall and twisted bronze leaves. Purple loosestrife (Lythrum salicaria) has spires of reddish-purple flowers and lance-shaped leaves. The water forget-me-not (Myosotis palustris) has sky-blue flowers with yellow eyes all summer long.
All these plants are valuable for breaking up the hard outline of a pond. In deeper marginal water you can grow the water flag (Iris pseudacorus), a tall, bright yellow variety of iris, but it may be too vigorous for smaller gardens.
Plants for formal ponds. Plants with floating leaves and flowers, such as water lilies, are the obvious choice for formal pools. Nymphaea ‘Froebelii’ has deep red, starry flowers and purple-green rounded leaves. Nymphaea ‘Marliacea Chromatella’ is a yellow-flowered variety with olive green-streaked leaves.
Arum lilies do not float but stand upright and look marvellous at the edge of a pond where their arrow-shaped leaves and pure white flowers can be reflected in the water. Zantedeschia aethiopica is the hardiest and will withstand several degrees of frost.
Bog and moisture-loving plants. Numerous colorful plants will grow happily in soil that is kept permanently wet. The water violet (Hottonia palustris) has pale lilac flowers and likes full sun; Anemone rivularis has blue or white flowers from spring into summer; and ragged robin (Lychnis flos-cuculi) is a very pretty sharp pink flower with ragged petals, which used to be common and now seems to be rare in the wild.
Rodgersia aesculifolia is another tall, stately plant with leaves like the horse chestnut tree and plumes of tiny, fragrant white flowers tinged with pink. Rheum palmatum also has large, handsome foliage and unusual flower spikes on reddish-purple stems.