On the west side of my house, large maple trees shade the foundation. My house sits on a dry knoll and the maples take any moisture that's left. Some gardeners combat dry soil by watering on a regular schedule. They water every day or every other day. I can't figure out if they own the plants or the plants own them. I prefer sporadic watering. This means I get to enjoy watering when I want to water. When I don't feel like watering, the plants have to hang tight until I want to water again.
Someday I may find a list of shade loving plants that thrive on sporadic watering in heavy clay soil. Meanwhile, I'm figuring it out a few plants at a time.
I placed a camellia (Camellia sasanqua) in this area to give some evergreen backbone. It isn't as happy as other camellias in my landscape but it does okay. On another corner I planted a gardenia (Gardenia radicans). I am still evaluating gardenia, but this one has flowered several times. This may not be the best location, but the shrub will live.
Traditional shade shrubs found in local nurseries include aucuba (Aucuba japonica), mahonia (Mahonia sp.), and peris (Peris japonica). Of those, the mahonia would do the best in a dry site. Aucuba and peris should live. They might even thrive with well-amended soil and a good mulch.
Hosta (Hosta sp.)is the first plant most people think about for dry shade. Hosta would do better with moisture but survives between watering. Hosta has done well for me.
I have planted variegated Solomon's seal (Polygonatum odoratum "Variegatum"). A close relative, also called Solomon's seal, lives in native areas on my property. It does okay in dry hardwood forest. My plant hasn't thrived but it has increased. It increases faster in more sun but burns out in the summer. In full shade it should contribute beauty all summer. I can't vouch for summer long beauty but I do know it isn't immune to dogs, kids and garden hoses. Maybe this year it will last all summer without getting knocked over.
The bleeding heart (Dicentra eximia or Dicentra spectabilis) looks good with hosta but it needs moist soil for best performance. Dicentra spectabilis goes dormant without moisture while Dicentra eximia dies. In my situation, I would have to water anytime we get a dry spell so I am going to resist buying this one.
I'm going to try Coral bells (Heuchera spp.) next. This perennial does okay in dry shade. The reference books recommend moist partial shade. I have seen Heuchera, or a close relative called foamflower (Tiarella sp.), living in a natural area on the banks of the Yakin River. The site was a thin layer of soil over rock. I'm sure this site dried to a crisp in the summer. This plant and some moss survived. Five species of heuchera live in North Carolina but about 70 more species live in the Rocky Mountains. In the garden center, you will likely find Palace Purple. Palace Purple's parentage is unclear but it could be Heuchera micrantha. Heuchera americana or Heuchera sanguinea cultivars will also grow here in Cabarrus County. Mail order sources offer heuchera cultivars with silvery leaves, or variegated leaves. You can also have a choice of flower colors from white to red. Foamflower has also made it into the nursery trade but in fewer flavors.
A good complement to Heuchera is Pulmonaria (Pulmonaria spp.). This plant looks like it should be a house plant, but it is perfectly hardy even at 20 or 30 degrees below zero. Local gardens seldom include this plant, so I don't know for sure how it will tolerate sporadic watering.
Garden writers always mentioned astible (Astible x arendsii) as a shade plant. If you were standing in the garden center making a decision based on beauty, you would choose astible. In a moist garden that decision would be okay, but not in my garden. I will never buy astible. Well, maybe I would buy one in a moment of weakness. I can always tear the label off and tell my wife it's an annual.
Lenten Rose (Helleborus orientalis) does okay in shade. A lot of interest runs the costs up a few years ago, but you can buy them cheaper now. You can also dig a Lenten Rose from somebody who already has them. In moist conditions they come up everywhere. In drier sites they may not be as happy, but they will still live.
I have transplanted some blue eyed grass (Sisyrinchium sp.) over to the dry, shady spot. Blue eyed grass grows wild on my property and I rescued this one from the lawn. I also have a small yellow flower transplanted from my property in Montgomery County. So far I haven't figured out its name.
Foxglove (Digitalis) is supposed to do well in shade. Mine didn't do much on the dry shady side but I planted another one on the east side of the house and it reseeded this year.
I have plugged in coleus (Coleus x hybridus) and impatiens (Impatiens wallerana) as shade loving annuals. These stayed fairly small under my sporadic watering scheme.
I have seen several spectacular ferns in various local landscapes. I often think of ferns as moisture loving plants but the bracken fern (Pteridium aquilnum) loves dry soil. I generally see it in a little more sun than I have. A more dainty fern, Ebony spleenwort (Asplenium platyneuron), also grows in dry soils. I have even seen this native fern growing in a little soil high on a rock wall.
If you have a dry shady spot, I hope this has given you some ideas and a little bit of encouragement.
Article was written by David Goforth Agriculture Extension agent North Carolina Cooperative Extension Cabarrus County Center. Visit my homepage http://cabarrus.ces.ncsu.edu/ or http://cabarrus.ces.ncsu.edu/index.php?page=lawngarden or my blog http://gardeninggurugoforth.blogspot.com/
Contact me at David_Goforth@ncsu.edu. Reviewed 2007.