Rockery Plants - Part 2

OK, here's Part 2 of our virtual plant identification tour of Seattle rockeries.

This is Bergenia crassifolia, or winter blooming bergenia. It is also called "pig squeak" because the leaves make a squeaking sound if you rub them when they are wet. This is an evergreen perennial that requires little care. Just cut away old or cold-damaged leaves and faded flowers to keep it tidy.

These chartreuse flower heads belong to Euphorbia (I'm guessing this is a young specimen of E. chariacias wulfenii) a large genus of plants that includes the poinsettia (E. pulcherrima). Be careful handling these plants. They have a milky, white sap that is very irritating to the skin - I always wear rubber gloves when working with them, having been burned (literally!) in the past.

Along with them, a collection of English bluebells have taken up residence. Rarely planted on purpose, you'll find these cheerful blue flowers in gardens and rockeries everywhere in Seattle.

Speaking of blue flowers, these are grape hyacinths (Muscari sp.) These also happily multiply wherever they are planted. The red plant below them is a variety of Sedum.

Of course, rockeries are not all planted with ground covers and small perennials. When the planting pockets are large enough, small trees and shrubs can do quite nicely. Here at the top of the rockery is a weeping Japanese maple (Acer palmatum 'Dissectum Atropurpureum'), below it is David's viburnum (Viburnum davidii), and at the bottom, lavender (Lavandula sp.) is blooming.

Rockery gardening can be challenging because the planting spaces are often quite small and they dry out quickly in warm weather. Watering can be difficult because the force of the water stream can wash away some of what little soil is there. But after some trial and error, you will find a planting combination that will thrive with a minimum of care.

Missed the first part of the tour?
Go back to Part 1.

Rockery Plants - Part 1

As I said in my post on retaining walls and rockeries, Seattle is a city built on hills. Those hills are terraced with miles and miles of rockeries, which are planted, both accidentally and on purpose, with thousands and thousands of plants. Many of these plants bloom in spring, lining our streets with mini-explosions of color.

If you have ever wondered what any of these plants are, I'm here to help. In the next two posts, I'm going to take you on a little virtual tour of Seattle rockeries to help you identify some of the many plants you see blooming there this time of year.

This is a classic rockery plant combination: yellow Alyssum 'Basket of Gold,' paired with purple Aubrietia deltoidea. Aubrietia comes in both dark and lighter shades of purple; less common is a variety with deep rose colored flowers.

Candytuft (Iberis sempervirens) is a tough perennial with a long bloom time. It's one of the true bright whites (along with shotweed flowers) that you see early in the season. If you have this plant in your rockery, be sure to shear it after blooming to keep it from getting leggy. 

The red and green succulent plant spilling out onto the stairs is one of the many varieties of Sedum available in our area. Sedums are particularly well suited to life in a rockery because they require very little in terms of water, nutrients and care. 

The pink flowers on the left are heather (Erica sp.), the medium blue flowers in the middle are Lithodora, and the light blue flowers at right are periwinkle (Vinca sp). As with candytuft, all three of these should be sheared or cut back after blooming to keep them compact. In the lower left corner, new fronds, called fiddleheads, are emerging from a fern. To keep ferns looking tidy, cut away old, dried out fronds in late winter/early spring.

Wait! There's more:

Rockery Plants - Part 2

Retaining Walls & Rockeries

Seattle is a city built on hills. Our houses are arranged on these hills like a patchwork of theater seats, taking advantage of the remarkable views our part of the world has to offer. Of course, keeping all of these sloping properties from sliding to the bottom of their respective hills is a challenge. And rising to this challenge are thousands of retaining walls and rockeries. If you have a sloping property and need to build a retaining structure, Seattle is the place to explore for ideas. Here are a few of them.

For people who complain that concrete is too boring, this is a clever way to use the material. These walls form the front edge of a yard with a red brick house. The homeowners could have chosen masonry to match the house, but masonry walls would probably have been more expensive than these tinted concrete ones. A few bricks attached to the walls echo the brick of the house, making for a cohesive hardscape design.

Here is a concrete wall system that is clean and sophisticated. Finished with parallel grooves along the top and featuring built-in lighting for the steps (note the small rectangles along the wall), this is one of my favorites.

This type of wall, made of river rock, was popular in the Craftsman era. I doubt anyone builds walls like these much anymore. This one is in better shape than most I've seen and the plantings add to its charm.

Today concrete walls with a stone veneer, like this one, are more popular. These can be constructed more quickly, easily and affordably than walls built with stone only.

My landscape design instructor used to say, "The trouble with common plants is that they are used commonly." The same can be said of common building materials, like this concrete block. I know that these block systems are affordable and relatively easy to install. But aesthetically, they don't do much for me. Here, however, is a winning combination of planting and hardscape. The block walls literally set a stage for the plant material, which is what draws the eye.
[For more ideas, take a look at "Hillside Landscaping: A Complete Guide to Successful Gardens on Sloping Ground," from Sunset Books.]
Note also that instead of one very tall wall, there are two tiers, one set back from the first. From a design standpoint, this is good because it adds layers of color and texture instead of a monolithic and forbidding looking structure. From a legal standpoint, the design works, too. According to the building code in Seattle, any structure over 4 feet tall is considered a retaining wall and a permit is required before it is built. These tiered walls are each at or under 4 feet, thus avoiding the need for a permit.

Of course, no article on garden walls in this area would be complete without a mention of the classic Seattle rockery. Usually made of basalt, which is abundant in the Northwest, these walls are constructed without mortar. The gaps between the stones are perfect planting pockets for gardeners to fill with color, as you see below.