Some fabulous plants will only grow in soil that is permanently moist, and even if you don't have a boggy area in your garden, it's quite easy to create one.
When to Start: Anytime
At Its Best: Summer
Time to Complete: 2 days
Next to your pond or other suitable area, use a garden hose to make a curved and natural outline for your bog garden. Dig it out to a depth of about 24 inches and set the soil aside.
Lay the liner in the hole and push it into the corners. To hold it in place, overlap the edges of the hole with at least 12 inches of liner, and weigh it down with bricks. Make sure the liner isn't pulled tight or else it could rip when filled.
Although you want the soil in your bog garden to be moist, it shouldn't be completely saturated or it will lack oxygen, which is vital for healthy plant roots. To provide some drainage, pierce the liner with a garden fork at 3-foot intervals.
To ensure that the drainage holes don't become blocked over time, causing the soil in your bog garden to stagnate, cover the liner with a 3-inch layer of gravel.
Fill the bog garden with the soil you excavated when digging the hole, together with some organic matter, and press it down. This will settle the liner into its final position. Use sharp scissors to cut any visible excess liner from around the edges.
A perforated hose, which allows water to seep out slowly, will make it easier to keep your bog garden wet during dry periods. Sink it into the soil all the way around the inside edge of the bog garden, leaving just the hose attachment above ground. You can then simply attach a garden hose to it when necessary. Since the hose attachment will eventually be hidden by plants, remember to mark its position in the garden.
Position your bog plants, still in their pots, and when you're happy with the design, plant them so that they are at the same level as in their pots, or slightly deeper. Mulch with organic matter. Keep well watered until the plants are fully established.
Excerpted from How to Grow Practically Everything
© 2010 Dorling Kindersley Limited