Q: We have a concrete retaining wall around the north side of our property in Magnolia. It's protected from most wind and does not get a lot of sun except in the summer.
The planting area between the wall and the sidewalk is about 18 inches. Plus, the sidewalk slopes downhill, meaning that the east end of the wall is only about 18 inches high, while the westernmost end is about 7 feet high. So, I likely will need a variety of planting to camouflage the wall.
I am at somewhat of a loss for suggestions of plants that could be pruned to stay fairly low yet, toward the west end, be allowed to gain height and be structural enough not to sag or slump.
A: It sounds as if you're looking for narrow, shade-tolerant plants in a variety of heights. Since the planting bed is next to the sidewalk, you'll want to avoid barberries or any other prickly or sharp plant that might bother passersby.
Not every landscaping situation, especially such a challenging one, needs to be solved with plants. A tall art piece or mosaic bolted to the wall, or a decorative trellis planted with sasanqua camellias would be good alternatives to break up the expanse of concrete where the wall is highest.
Also, don't feel you need to cover the ground with plants. Using larger rocks with interesting shapes or smooth, black Japanese stones could be easy-care and attractive alternatives.
If you'd like a sleek, tailored look, you could plant a low hedge of Buxus sempervirens 'Suffruticosa,' which is a dwarf boxwood with a tight, dense form that tops out at 4-5 feet but can be clipped to stay lower.
Its new growth is lime green, and in summer the leaves are bright, shiny green, which would contrast well with the concrete wall. I'd think a distinct horizontal line would look good against the slope of the wall.
At the end of the bed where you want more height, you could plant a row of heavenly bamboo, or nandina, which grows into an airy screen. For a pleasing foil to the solid green hedge, take a look at Nandina 'Plum Passion,' with purple-red new leaves and winter foliage.
If you want more of a seasonal garden, instead of the boxwood hedge you could plant perennials such as wood spurge (Euphorbia amygdaloides var. robbiae), which will rapidly fill in, with evergreen leaves and chartreuse flowers in spring.
Smaller hostas and ferns, mixed with the hardy Geranium phaeum, also called mourning widow for its maroon flowers and darkly blotched leaves, would be handsome, shade-tolerant choices. For color, you could edge in summer with violas or impatiens.
I'd suggest installing a drip system, or at least a soaker hose, in the planting bed so you can nurture the plants along. Also, be sure to use good, rich soil and mulch well to protect roots from drying out in summer and from cold in winter. You might want to check out municipal and shopping-center plantings, as at Bellevue Square and University Village, to see what plants you like that live comfortably in confined spaces.
Q: I'm having gardening friends from the East Coast visiting in April. I live in Tacoma and know about Lakewold — any other suggestions for gardens in our area to visit so early in the spring?
A: I bet your friends would enjoy the Northwest Native Plant Garden at Point Defiance Park, which is a lovely stroll and should have plenty of spring bloom next month. On your way to the park, be sure to swing by the exciting nursery Jungle Fever Exotics at 5050 N. Pearl St. (253-759-1669), a destination sure to make anyone from the East jealous they aren't gardening in our climate. If you're heading south, the Olympia Farmer's Market on Capitol Street (360-352-9096) is a fun stop for unusual plants, fresh and dried flowers as well as produce and crafts.
Valerie Easton also writes about Plant Life in Sunday's Pacific Northwest Magazine. Write to her at P.O. Box 70, Seattle, WA 98111 or e-mail planttalk@seattletimes.com with your questions. Sorry, no personal replies.
