If you have no space for a bog garden but would like to grow some of the plants that prefer damp soil, create a container display. Simply plant up a large, nonporous pot—made from glazed earthenware, synthetics, or galvanized steel—with your favorite plants to perk up a shady patio or poolside.
When to start: Late spring.
At their best: Early to late summer.
Time to complete: 2 hours.
You will need: Large, nonporous container, plastic sack, gravel, soil-based potting mix, well-rotted organic matter, bog plants; those we used here as an example are: Astilbe ‘Fanal’, Carex ‘Silver Sceptre’, Persicaria microcephala, ‘Red Dragon’.
Line the container
Select a large nonporous container and make sure it has a drainage hole; drill one if it doesn’t. Line the container with a thick plastic sack, such as an old compost bag. With a kitchen fork, pierce a few small holes around the sides of the sack, about 2 in (5 cm) from the bottom.
Prepare to plant
Fill the base with 3 in (8 cm) of gravel, which will prevent soil from clogging the drainage holes around the sides and create a water reservoir at the bottom of the pot. Then add a layer of soil-based potting mix with some well-rotted organic matter.
Add the plants
With the plants still in their pots, check that they will sit at least 2 in (5 cm) below the rim of the pot when planted. Then water the plants, and remove them from their pots. Place them on the layer of potting mix, and fill in around them carefully with more of the mixed soil and organic matter.
Mulch and water
Firm in the plants, water well, and add a mulch of organic matter. Set the container in a partially shaded area, and water frequently. Reduce watering in winter to prevent the soil from freezing. In spring, replace the top 3 in (7 cm) of compost with fresh material. Add slow-release fertilizer.
Large containers are ideal for bog plants because they hold more soil and water, and provide the best conditions for good growth.
Any plants that like boggy soil can be added to a container display, as long as you match the size of the pot to your plants. Check plant labels carefully for heights and spreads. For example, the gigantic leaves and stems of an imposing Gunnera manicata will need a large pot to support them, while a group of primulas will be happy in a smaller container. Most bog plants are fully hardy and can spend the winter outside, but choose a pot made from thick material to insulate the roots.