Bog Gardens – A carefully sited bog garden will substantially improve the look of waterside plantings around pond and pool edges, and will also extend the range of beautiful plants that can be grown. Remember only that these plants may thrive and seed excessively, so the same watchful eye must be kept on them as on the marginal plants.
Concrete and preformed ponds, being impermeable to water and usually sited in a sunny position, generally have very dry soil to the side of them, making them unsuitable for waterside plantings. Ponds made with flexible liners, and natural streams, both lend themselves to the creation of an adjoining area specifically intended to hold moist soil.
This is done by creating large but reasonably shallow depression, 45cm/18in deep, to one side of the pond. Line this depression with thick gauge polythene, which has had a number of holes punched in it. The reason for puncturing the liner is to prevent water lying permanently in the bog area. Once put in place, these drainage holes should be covered by gravel so that the soil which comes next does not clog them.
When adding the soil, bank it up on the side next to the pond, to create a shallow lip which will prevent water from seeping into the bog garden from the pool. The areas will then appear to be connected but will, in fact, be separate.
It is of course possible to create a quite separate bog garden, close to a preformed pond or in any other appropriate spot in the same way. Punctures in the liner will ensure that rainwater seeps slowly away. If acid-loving plants are to be grown, the soil of a bog garden should have a low pH and be enriched with fibrous organic material.
Natural streams, with sides which regularly flood, also provide perfect habitats for bog plants. If you are lucky enough to have a stream trickling through your garden, do not miss the opportunity to grow such lovely plants as the marsh marigold (Caltha palustris) beside it.
Gunnera in the bog garden
Irises
Marsh marigolds
Astilbe
Pickerelweed