Some spots in your garden might always have moist soil, perhaps because they’re shady and protected from wind, or perhaps because they drain slowly or collect water during rainfall and irrigation. Instead of trying to dry these areas out with drain lines, select plants that prefer wet soil.
Plants adapted to bogs and marshes thrive in conditions of constant moisture. Many of them grow happily with their roots under water. When selecting plants for these places, browse through the pages of catalogs or web sites that specialize in ponds and aquatic plants—most of them also carry bog plants. Since most bogs dry out occasionally, many bog plants also tolerate dry periods. You don’t need to create a bog where none existed before. It will be enough to plant them in the damp spot.
Another solution to wet spots is to raise the soil where you want to plant. A raised bed or a mound will drain quickly enough so the soil won’t remain moist. If the spot is only damp, without standing water, as little as 4 inches might be enough for small plants.
A third solution for spots that are deeply shaded with little air circulation is to grow a moss garden. Mosses thrive in such locations, and can be serene and restful. Plant some ferns or other shade- and damp-tolerant plants and position a few rocks for interest, and you have turned a wet spot into an enchanted dell.