Plants For Clay Soil and Dry Shade
Since my garden soil is mostly clay and I also have lots of shade, I'm constantly checking the gardening world for plants that tolerate both clay soil and dry shade. I've found quite a few that do and look lovely while doing it. For this article, shade is considered four hours or less of sun each day, such as two or more hours of sun in the morning and/or evening. Dry shade would be the area among a group of high-canopied trees, either evergreen or deciduous. It could also be the outer rooty area under large shrubs such as viburnums.
Nothing, however, will grow under the low limbs of evergreen trees. Two things make this area "dry". One is that the canopy of tree leaves doesn't allow much rain to even reach the ground and soak into the soil. The other is that the roots of the trees and shrubs remove a lot of the moisture from the ground so there is less soil moisture for the smaller plants planted underneath.
When planting, try not to remove roots more than one inch in diameter; plant only plants that can tolerate dry shade in between the roots. I plant (and weed too) only when the soil is moist, such as after a heavy rain. Give the plants lots of water and plant them properly as outlined in my article on "Establishing Your Plants" on the Planting and Maintenance page. Check them frequently to make sure that the tree roots in the area haven't drained the area dry. During the first growing season you may have to water plants in these areas more than once a week. This is especially true around plants such as beech, maple, and viburnum.
Many plants that tolerate dry shade don't thrive as they would living under kinder conditions, but they do survive. They may not be as dense or as tall as they would normally grow. They may have fewer flowers and flower for a shorter period of time. But getting plants to survive, bloom, and look good in such inhospitable surroundings makes this effort worthwhile.
Don't expect to plant and forget. Any plants living under dry shade conditions should be mulched to conserve moisture and must be watered on a regular basis if they don't get enough rain. Even if it does rain, because of the tree or shrub canopy of leaves above the plants, not enough rain may be getting through so even after they've been established check them often and water as needed.
In most instances I've only included the genus and species names for each plant. Many of these species have wonderful cultivers that should be able to be used as well. In many instances the cultivars are even better plants than the species itself. Cultivars are always shown in single quotes such as the 'White Nancy' cultivar of the species Lamium maculatum.
I've grown about 80% of the above plants under clay soil and dry shade conditions and they've done well. For the other 20%, I've watched their progress in other dry shade gardens.
When deciding what plants to plant, keep in mind that most shade plants don't flower for long periods so it's important to look at the plant's other characteristics including how good its leaves look after flowering (the leaves of many perennials turn yellow and brown after flowering and wither away).
If you've been gardening for a while, you know that green is not just one shade of green but many different shades from light green to dark green. Green can also have other colors mixed with it. Yellow makes green look chartreuse and blue makes for a blue or bluish-green look. Of course, there is also variegation where there is more than one color present, such as hosta leaves with white edges and blue-green centers for instance. So, it's important to think about leaf color as well as flower color when selecting for shady conditions. Several plants with green leaves can be set off by plants having variegated leaves, or blue or yellow tones in the leaves.
Another important aspect of designing in the shade is leaf size. The small leaves of yews and boxwood can be juxtaposed with large-leaved plants such as Hosta sieboldiana or Heuchera villosa.
A great dry shade combination of plants would be a carpet of Sweet Woodroof, with a grouping of Liriope muscari ‘Variegata' providing grass-like tufts, a large blue Hosta sieboldiana ‘Elegans' in the background to one side and on the other side to balance the picture a large grouping of Persicaria virginiana ‘Variegata' with their larger variegated leaves showing off through the summer.
Another plant combination would be Aucuba japonica ‘Variegata', three Hosta ‘Fried Bananas' with chartreuse leaves, over a ground cover of Phlox stolonifera with blue spring flowers and a grouping of Polygonatum odoratum ‘Variegatum' for height.
As you can see, there are so many possibilities for providing color, flowers, and fragrance that there is no reason to miss out on the opportunities of gardening in dry shady areas.