Have you ever thought about having a bog garden? It means that you can grow a wider range of plants, especially if your topsoil is quite sandy (see types of topsoil article here). It’s a particularly good way of using an old pond, but you can also make a new bog garden using pond liner. Autumn or winter is a good time for this project, so it will be ready for planting in spring.
Making the bog garden
You can use an old plastic pond as the base, or buy some butyl pond liner. If your pond is already in place, then all you need to do is drain it and clean it out. Otherwise, you will need to dig a hole. Mark out the area with string. You will have to dig it out to about 45cm/18in, so make sure it’s not too large. Keep the soil as you dig it out, as you’ll need it later.
Once the hole is ready, then line it with pond liner, weighted down at the edges with stones or bricks, or put in the old pond. Pierce the bottom of the hole or the liner at intervals for drainage. Line the bottom with a layer of gravel or grit, to improve drainage.
If you dug out your own hole, now is the time to return the soil. If you used an old pond, you will need to buy topsoil, available from topsoil suppliers. If you need gravel too, it’s probably a good idea to order them together to save money on delivery! Let the soil settle naturally over several weeks, and top up as and when necessary before planting. Keep it weed-free over winter until you’re ready to plant.
There are a wide range of plants suitable for a bog garden, ranging from ordinary perennials that are quite happy in moist soils, such as hostas, through to genuine marginals and pond plants like Pontederia and flag iris (Iris pseudacorus). As always when choosing plants, think about having some tall and some spreading, and also about your season of interest.
One word of warning: Houttynia ‘Chameleon’ or ‘Flame’ is a foliage plant often recommended for bog gardens. It is very pretty, with lovely red and green variegated leaves, but it will spread like mad in ideal conditions like a bog garden.
Your plants will need the usual maintenance in a bog garden: splitting after a few years, and so on. You will also need a way of keeping it damp. Either use a watering system, or incorporate a length of porous hosepipe in the base of the bog garden, with the end leading out to an easily-accessible point. You can then irrigate through it and keep the soil damp all year.