cascading plants for retaining walls

I’m looking to plant in a narrow strip on our retaining walls some “spiller” plants which will overhang the walls (which face north).

I’d prefer evergreen plants which would fill in fairly quickly,
but I could also mix in slower-growing and deciduous plants. There’s great drainage since I have gravel reservoirs
behind each wall, and the part of the plant above the wall will get part to
full sun, though I could overplant them if necessary for a plant that couldn’t
handle full sun.

I would like plants with interesting foliage and form to soften the look of the walls, and so would prefer a furry look to a spiny one. Flowers and fragrance are less
important though always nice, and I’m hoping to have at least 2 or 3 different
plant types with different colored foliage (shades of green are fine).

Some of the plants that occur to me, based on the description of your site, are
Brunnera macrophylla, Epimedium, Geranium phaeum, Stachys byzantina, Lamium
maculatum, and Liriope. Of these, the Geranium and Lamium will trail somewhat, while the others are essentially upright.

Graham Rice’s article on the Royal Horticultural Society site features a selection of recommended trailing (or spilling) plants. Here is another good list of trailing plants for walls.

You could also try entering your site requirements into the plant-finding and
plant selection web pages below:

Great Plant Picks (a local site)

King County’s native plant guide

Missouri Botanic Garden Plant Finder

Royal Horticultural Society Plant Finder

The Miller Library has many books on gardening in the shade, so you may wish to
come in and do some research to help you in your plant selection. Here is a booklist that may be of interest.

planting under a sycamore tree

We have a very large beautiful sycamore in our back yard. My roommate
thought it would be nice to build a flower garden around the base of the
tree, but something tells me that doing so would be harmful to the tree’s
root system. Is this true? I would love to hear your thoughts.

I think it should be safe to plant
shallow-rooted, shade- and drought-tolerant perennials and small bulbs
under your sycamore (I’m assuming you mean Platanus species, and not
sycamore maple, which is Acer pseudoplatanus). You just need to be
careful not to pile soil on top of any exposed roots, and try not to
scrape or scuff any roots when you are planting. This tree does have
spreading roots so they may extend out some distance.
More information about the tree can be found on the pages of the U.S. Forest Service.

Some of the plants which may work well in your garden are:

Lamium (but not the invasive Lamium galeobdolon)

lawn alternatives and planting under pine trees

Our house is on a corner lot. The side yard has a very small slope with big rocks along the edge. Presently it has a variety of flowers such as lavender that bloomed last summer.
However, my question is what kind of ground cover can I put there, other than grass, that would look good and be evergreen.

Secondly, there are two big pine trees at the corner. What are my options for plantings beneath these trees that would give it a pulled-together look?

I am guessing that the spot receives a good amount of sun, since you have lavender Lavandula that flowered there in the summer. Were you looking for a groundcover that will tolerate people walking on it, or did you want somewhat taller plants that will blend well with the lavender?

If you plan to walk on the area, you might want to consider chamomile (Chamaemelum nobile) or creeping thyme (Thymus serpyllum).

There are many great choices for plants not intended to be walked on, and I recommend that you take a look at some of the resources we have in the Miller Library so you can find the plants that most appeal to you. I recommend the books Gardening with Groundcovers and Vines by Allen Lacy (HarperCollins, 1993), and Perennial Groundcovers by David MacKenzie (Timber Press, 1997) as starting points.

Plants that are evergreen (or ‘ever-grey’) and might go well with lavender are Santolina, Helianthemum (sun rose), Teucrium chamaedrys (germander), and Ceanothus thyrsiflorus (creeping blue blossom ceanothus).

For the spot under your pine trees, you will need plants that tolerate shade and do not have large root systems. I would try Lamium (dead nettle), which comes in several foliage and flower colors, and I would avoid Lamium galeobdolon, a species which is considered a noxious weed in King County. Vinca (periwinkle) might also work. The Lady Bird Johnson Wildflower Center has information on planting beneath pine trees.