By Ian Thornhill and Adrian Thomas Reviewed by Steve Head
Ponds need plants. To be visually attractive as well as a good habitat for animals, ponds need to have a good quantity of vegetation of several varieties. The only ponds that don't need plants are essentially out-door fish tanks that people maintain with pumps and filters to house koi carp.
Plants provide food, shelter, nutrient removal services and even oxygen so that aquatic animals can thrive. When they die back, their decay ensures that the next generation of plants have substrate and fertiliser from which to succeed. Much as we may like looking into the limpid depths of open water, the tiny and tasty animals that live in your pond much prefer the shelter of vegetation, so most of the animal life in ponds is in the shallow water at the edges where plants grow best, and they can hide in complex networks of roots and stems
You don't in theory need to plant-up a new pond, since plants will arrive in their own time, blown in as seeds, or carried on the feet of birds. New countryside ponds may best be left to mature without planting, but few gardeners will have that amount of patience.
How much cover?
There is no golden rule about how much vegetation a pond should have, but the National Amphibian Survey
found that amphibians avoid extremes of vegetation coverage, occurring significantly less frequently in ponds containing either no emergent vegetation at all, or more than 75% cover. We suggest you should aim for about 50-75% of the water surface covered with vegetation. Don't spend a fortune buying plants to fill that area, they grow and expand astonishingly fast.
Natives or non-native plants?
Where terrestrial plants are concerned, we consider appropriate many non-natives a positive benefit to wildlife in the garden - see our page Gardens - native and non-native species
. In ponds, this isn't so clear. Many aquatic plants can grow extremely rapidly, and not only will take over a pond completely, but can be a disaster if they find their way into the countryside where if they have no natural controls, they can become massive problems. See below for more warnings on this. Be aware though that many native plants such as Norfolk reed and reed-mace are also far too vigourous for normal garden ponds.
There are a large number of extremely attractive and garden-worthy native plants at our disposal, and we recommend that you primarily use these in your garden. There are non-natives that are safe to use, especially among the marginal plants, and some are very attractive. If in doubt, look up a potential non-native on offer to see if it associated with problems. Plantlife has a useful leaflet
listing useful native and non-native pond plants as well as flagging up ones to avoid.
For detailed planting advice, look at Ian Thornhill's leaflet "Planting up ponds".
What follows here is a brief introduction to water plant types.