Plants with hidden depths

Water lilies are probably the most popular of all pond plants; they come in sizes to suit any pond, even one in a bucket, and they can provide an almost continuous show of blooms throughout summer. Not only do they look lovely, but their leaves also provide a protective cover for fish under large leaves, and shade the water from sunlight, thus keeping down algae.

But not everyone has the knack of growing these delightful flowers, so perhaps they should consider something different. Basically, there are four groups of plants for the garden pond – submerged (or oxygenating) plants; the aforementioned water lilies; floating plants and marginal plants, and all can make or break a pond. Canadian pond weed, for example, forms attractive underwater growth and uses up the minerals and nutrients in the water which would otherwise encourage algae growth. It's a bit like an underwater Hoover, keeping the water clean. The biggest drawback is its ability to grow quickly – think weed and think having to keep it under control.

Perhaps water hyacinth, which floats rather than sinks beneath the surface, would be better. Allow just one plant for every 10 square feet of water surface.

And don't be tempted by duckweed – it has the invasive tendencies of Napoleon.

But if you want your pond clean, clear and unsullied by plants, just grow marginals in the shallow water around the edge. The roots are submerged but the stems and leaves stand clear. The finest are the flag irises, with their sharp, sword-like leaves topped by incredible blooms. But be warned; snails like them as much as gardeners.

Flowering rush, marsh marigold and primulas are also worth considering.

YP MAG 7/8/10