Ask the master gardeners

Q: One corner of my property is shady and tends to become boggy. What are the best perennials for wet shade?

A: Before planting, first test your soil to make sure that it is appropriate for bog plants, as most prefer acidic soil. Use tall plants for the back of your planting area.

Black cohosh (Cimicifuga racemosa) is a deer-resistant native plant, 5  to 8 feet high, with dark green fernlike foliage and long arching white blooms that form seed pods for winter interest.

Indian rhubarb (Darmera peltata) has tall pink flower spikes in mid-spring, followed by 1-foot leaves atop 3-foot stalks. It lends a tropical look, though it’s hardy to USDA Zone 5.

To set off your foliage plants, plant toad lily species (Tricyrtis hirta and T. formosa), both graceful plants with stalks of star-shaped white flowers. The native Lobelia cardinalis (cardinal flower), which attracts hummingbirds and butterflies, provides lovely red accents, and Ligularia dentata (leopard plant) produces clusters of yellow flowers in summer.

Shorter plantings toward the front of your wetland area might include Lousiana and Siberian irises (Iris sibirica and Iris louisiana), creek monkey flowers (Mimulus guttatus or M. ‘Orange Glow’), Siberian pink cups (Baldellia ranunculoides) and golden buttons (Cotula coronopifolia).

A border of blue forget-me-nots (Myosotis palustris) can be accented with curly watercress (Barbarea verna praecox), which adds texture to the border and variety to your summer salads.

As a tropical accent, consider a shade-tolerant canna such as Canna ‘Stuttgart,’ which reaches 5 to 8 feet high with white-striped green leaves and yellow flowers, or the 4-foot-high Colocasia esculenta ‘Violet Stem.’ Both need to be dug up before frost and kept in a cool cellar until spring.

Among annuals, coleus and caladium species are interesting additions. In late fall, cut back any decaying foliage and mulch your boggy perennials with leaf cover or wood chips. Leave black cohosh until spring when the pink flowers of Indian rhubarb announce the beginning of another season.
—  Janet Cooper-Wetherly, Congers, master gardener, Cornell Cooperative Extension of Rockland