The Charleston Gardener: Shade Gardening
By Louisa Cameron
I so enjoy plants that bloom in the shade or have foliage that stands out in shady areas, as we have an urban garden and the neighborhood houses are right on our lot lines, blocking a good bit of the sun from the southern and western exposures.
Years ago, when we first moved to our current location, we had oaks, hackberries, cherry laurels, magnolias and hollies filtering out most of the sun and depleting the soil in every direction with their arm-size roots. It was a challenge that I attempted to meet by purchasing George Schenk’s The Complete Shade Gardener. Published in 1984, this fascinating paperback has a paucity of color photographs, but that didn’t matter; it is full of superb advice and is still one of my favorite reference books. One of the most interesting facts brought out by Mr. Schenk is pertinent to Charleston.
“In reading all that follows,” he writes, “please keep in mind the role of moisture in the air. Humidity plays a part in shade gardening as important as that of shade itself. Humidity acts on shade, altering its values. For plants, shade is strengthened by accompanying moist air and weakened by dry air. Due to differences in humidity, the life-giving powers of shade vary from one garden to the next.”
Mr. Schenk goes on in the same chapter to explain a dozen variants of shade: warm, cool, light, dense, etc. His attention to detail and his suggestions for under-tree plantings and soil amending are invaluable, and I consult his now-well-worn book on a regular basis. He also includes instructions on how to propagate ferns, and I still use his approximately 150-page list of plants with comments on where and how to plant them and how to use and care for them.
In September 1989, Hurricane Hugo changed the entire landscape of the city of Charleston. Approximately 70 percent of the trees on the Peninsula suffered destruction or damage. Many were torqued by the hurricane’s swirling winds and the numerous small tornadoes that spun along with the storm, resulting in a slow demise during the next few months and years. Our garden was struck by one such tornado cell, and our stately and enormously tall water oak was jerked out of the ground, leaving a crater where its root ball had been established. Lucky for us, the tree fell away from our house, but unlucky for a neighbor, the crown landed on a roof two doors down the street. A couple of magnolias and several “trash” hackberry trees were knocked down, and an overgrown cherry laurel was twisted and had to be removed at a later date. Tree service crews arrived from neighboring states, and the sound of chainsaws was a constant for many months. So much sun poured over the foliage-stripped area it is estimated the soil temperature was raised by several degrees. Many plants suffered sunburn and others were warmed into early spring bloom in late fall. It was a total disaster all the way around for just about everyone’s gardens.
We regrouped and embraced the sunlight that lit up previously shady areas. However, as we reworked the entire garden for the next few years, we planted fast-growing crape myrtles around the perimeter of the property and later put in dozens of camellias, sasanquas, azaleas and hollies, all of which need some shade. Twenty-three years later, we have shade again and have to have the trees professionally thinned from time to time.
For show and color, my favorite shade flowers are impatiens. Just keep them fed and clip them occasionally to prevent legginess. They now come in not only jewel tones, red and a range of pinks, purples, and oranges; I have also seen a butter-colored cultivar. The New Guinea varieties can tolerate some sun and are a happy choice for hanging baskets. Begonias also come in a wide range of colors and varieties, and I use them every year. Some come back from a mild winter. They are easy and quick to propagate.
The heady fragrance of gardenias and ginger lilies (Hedychium coronarium) is a dreamy summer pleasure, and both plants make excellent, if short-lived cut flowers. There is a wide range of gingers that will flourish in our climate. They multiply readily, forming colonies of color and fragrance. Some will grow at least four to five feet tall. We have tried orange and yellow varieties, but the squirrels find them and dig them up. So far, the little demons haven’t discovered the blue ginger a friend gave us last year, and they don’t seem to favor the orchid-like Hedychium coronarium.
As for shrubs, hydrangeas are at the top of the list. There are hundreds of different hydrangeas and the nurseries always have them in stock. We have at least half a dozen oak leaf hydrangeas on the shady side of the garden. I am adding at least one new variety of hydrangea each year and rooting some of my prettiest purple-blue ones. I have tried for years to turn one long-lived pink specimen some shade of blue by feeding it sulfur and acidic fertilizer, but it’s too close to the lime-leaching mortar of a nearby brick foundation, and I now like having one pink plant in with all the blue. The nursery trade has developed varieties that are red and some that are mostly green, in addition to the usual white, blue and purple ones. It’s fun to root cuttings and even easier to put a brick on top of a branch that touches the ground and let it root itself. Mahonias also grow well here and provide a lot of texture.
Podocarpus macrophyllus, or southern yew, is an evergreen conifer that likes some shade and is widely used for hedges. Extremely slow growing, podocarpus can be nicely shaped into forms or espaliered. It has slender, somewhat toxic dark green leaves.
Caladium bulbs are planted in late spring for their heart-shaped foliage of red, white, green and every variation of these three colors. I put them under trees and in large pots to brighten up all-green or dark areas. I think they can be dug and held over the winter in sawdust if they are kept dry and cool, but I have never tried it. An air-conditioned garage would be ideal.
Other shade-loving or shade-tolerant plants with interesting foliage are aucuba (gold dust shrub); fatsia (sunlight reflects off of the shiny palmate leaves); farfugium (tractor seat plant) that shoots up tall stems with yellow flowers; variegated giant liriope; foxtail fern, Huguenot fern (lacy and a strong climber) and bamboo. If you plant bamboo, make certain that it is a clumping variety or it will take over the entire garden.
I do not advise planting tetrapanex, the rice paper plant, as it is not only invasive and hard to destroy but it also produces fine pollen that is highly allergenic. Chinese ligustrum, which is sterile and has no flowers, tolerates part shade and has fine-textured chartreuse leaves. It tolerates pruning and shearing and has grown to about six feet tall and five feet wide for us. Variegated privet (we have the California variety) has also performed well and can be shaped. Native plants are always a good choice and need less care than some fussy hybrids.
For groundcover, I find it hard to beat ajuga, which comes in lots of sizes and shapes and has a variegated cultivar. Ajuga, or bugle weed, spreads nicely and has lovely blue blooms on a short, upright stem. Ardisia, also called marlberry, is another groundcover with a choice of several cultivars. It is a reliable woodland plant but will not tolerate several days in a row of hard freezes. A bonus is its bright red fruit.
For areas where almost nothing will grow, umbrella grass (Cyperus alternifolius) is a good choice. Thank goodness it is easy to pull out of the ground because it is one of the most invasive plants I have ever put in the garden. Another invasive that has beautiful anemone-like white flowers is eomecon. I have it planted at the foot of our bamboo, which screens the back of a neighboring house.
Some gardeners have luck with lamiums, but I have lost many a plant. I tried violets, but they got away from me and invaded all the paths, so now they are on the weed list. One delightful but sometimes hard to find groundcover is the strawberry begonia (Saxifraga stolonifera), which grows low to the ground but sends up delicate pink stems with tiny white flowers in early spring, about the same time that the ajugas are blooming. I also planted pachysandra, but it succumbed to the heat.
Dogwoods, which used to be seen all over the South, were lost en masse to anthracnose, a disease caused by the fungus Discula destructiva. Because the fungus thrives in wet, cool weather, it is best to order dogwoods from a reliable arborist or nursery. They are also susceptible to powdery mildew, which is controllable, and to deer, which are not so controllable. However, they are glorious understory small trees that put on such a show in pink or white that it may well be worth the effort.
I bought a dozen or so cyclamen to brighten up some of the larger planters this spring, and I am trying my best to keep them alive. It was lovely and cool through the middle of May, but with the recent heat I think that the cyclamen probably won’t make it past the end of July, so I might have to treat them as annuals, the same way I do the foxgloves. I did get a couple of dozen plants from the few foxgloves that I let go to seed, and I have potted them up so that I can nurse them through the summer.
Hostas are a delight to use just about anywhere in the garden. There are hosta-specific websites, nurseries and books devoted to this plant that loves shade and blooms purple or white along sturdy stems. The main problem with trying to grow them is that they are a favorite food of slugs, snails and deer.
This article has barely touched the surface of the hundreds and hundreds of plants that will tolerate at least some shade in our climate. Be sure to remember that many plants need more water than you might think if the season becomes dry. It is a lot of fun to experiment, and I would advise taking a notebook and camera or a smartphone for making notes when going out and about and when visiting nurseries, plant centers and garden organizations’ sales. Annual garden tours can be enlightening and are always a delightful way to get new ideas.
Louisa Huger Pringle Cameron is a native Charlestonian married to Price Cameron, a retired plastic surgeon. She is the author of three books on the gardens of Charleston, enjoys duplicate bridge and is a proud grandmother of three.