Boggy soil can be a bit of a black hole in a garden. Not only is it a difficult area to cultivate and unpleasant to plant, but unless you choose exactly the right specimens for this inauspicious spot, they will disappear without a trace as their roots rot in the airless, waterlogged soil. As a result, boggy areas are often left neglected, only colonised by troublesome weeds, such as mare’s tail and sedge grasses. But it needn’t be so.
In fact, a patch of boggy soil should be viewed as an opportunity to grow a different range of plants that are well adapted to the demanding soil conditions. By choosing the right combination of moisture-loving plants, you can create an attractive and unconventional feature that’s the envy of your gardening friends and neighbours. Best of all a bog garden will look lush and fresh throughout the summer, just as more conventional borders are running out of steam.

Why make a bog garden?

• Transforms an eyesore into an attractive feature
• Extends the range of plants you can grow
• Looks great in late summer
• Attractive to wildlife
• Associates well with water features
• Less work

To appreciate the oasis of lush foliage and colourful flowers to the full, you will need to provide all-weather access. This can be in the form of stepping stones or log rolls, or a slightly raised walkway made from rot-resistant garden decking. This will also enable you look after the plants more easily.
Bog gardens look particularly effective adjacent to water features, such as streams and ponds - providing a seamless transition from marginal plantings in the shallows, to conventional garden borders. Alongside natural ponds and streams the soil is moist, making planting straightforward, but next to man-made water features, the soil is likely to be much too dry for moisture-loving plants. The answer, here, is to create a false boggy area using a flexible pond-liner

 

Creating a bog garden

• Mark out the outline of the bog garden using a garden hose and dry sand trickled from an empty wine bottle. 
• Dig out a hole 30-45cm deep, placing the soil to one side.
• Line the hole with a flexible butyl pond liner and puncture it several times with a garden fork at the deepest point.
• Cover the bottom of the liner with several centimeters of coarse grit or pea shingle to prevent soil blocking the holes.
• Replace the excavated soil, mixing in loads of well-rotted organic matter to make it nice and spongy.
• Allow the soil to settle for a week or so and top up as necessary.
• Plant up the bog garden and water well.
• Lay leaky pipe over the soil surface to make watering easier during dry spells and disguise it with a layer of organic mulch.

Bog gardens can look effective where there isn’t a water feature, too. Ideally choose a low-lying spot where a boggy patch might naturally occur. In one garden I created I used a collection of native marsh orchids at the edge of a group of mature trees. I chose a combination of good garden plants that appreciate having moist roots including Primula vialii, Lobelia cardinalis ‘Queen Victoria’, Astilbe 'Bressingham Beauty', Matteuccia struthiopteris and Rodgersia pinnata 'Chocolate Wing' with a stream of marsh orchids running through the centre.

 

Happy gardening!