We're beginning to see more of the summer sun as the fog burns off. By now, all of summer's flowers and vegetables should be in the ground taking full advantage. But what about those places where the sun never shines--those shady parts of the garden? Are they planted, or flowering?
If not, that can be this weekend's project because this happens to be a great time to be shopping for, and planting, those few plants that grow in the shade.
The two stalwarts of the shady garden--camellias and azaleas--are finished flowering and have already put on their new growth, but there are many other plants just beginning to flower. Hydrangeas are one--especially valuable because they flower after the camellias and azaleas, carrying the show into summer.
If You Prefer Blue
And, if you want a blue hydrangea, you had better buy it in flower. Hydrangeas must be turned blue in Southern California. The color comes from growing in an acid soil and ours is at best neutral and at worst quite alkaline. In New Zealand and in Seattle, where the soils are quite acid, they naturally turn a brilliant blue, but here we must tamper with the soil. If you scatter aluminum sulfate (Bandini packages it in five-pound bags) around the base of a hydrangea before it makes buds and then once again when the buds are about half-size, you may turn the flowers blue.
But, in my experience, not all hydrangeas will turn blue. It is best to buy one that is blue to begin with, and then try to keep it that way. Otherwise, you will have pink hydrangeas, and not a soft baby pink but a pink bright enough to compete with oleanders.
You can also choose a very safe route and plant a white-flowered hydrangea. In my own garden I've had great luck with one grown by Monrovia Nursery Co. that is simply labeled at nurseries as white. In the deepest shade and with aluminum sulfate sprinkled around it, it stays snowball white with just a tinge of green. In more light and with no aluminum sulfate, the white flowers have a soft, rosy glow.
Note that aluminum sulfate is not a fertilizer so you must also feed the hydrangeas at least once in the early spring. In the fall or winter cut back all the branches that have flowered to another side branch, or by half.
Porous Soil Needed
Hydrangeas like a rich, porous soil like you might find on a forest floor, as do almost all shade plants. Before planting, mix in quantities of organic soil amendment such as redwood or ground bark. I usually till in a six-inch layer of amendment, to a depth of about a foot, which is a lot of bags.
Abutilons are nearly perfect shrubs for a shady situation, and unlike the hydrangeas, they will also take a direct blast of sun during the day without wilting. This weekend is a last chance to plant them for they are finishing up their flowering and are beginning to grow right now.
No other plant in my garden flowers as long--10 months by my count--and it is one of the few plants that grows quickly to its appointed size and then seems to stop. Mine grow to about six or eight feet and then stay there, and they get there in about nine months, with lots of water and fertilizer. The best have large bell-like flowers, and in winter and spring they are smothered with them. Look around and you'll find all sorts of colors, from yellow into red with a nice apricot in between. There is also a pretty white. The one with small red and yellow flowers is more of a vine than a shrub.
Another champion shrub for the shade, even deep shade, is the dark, glossy green Japanese aucuba. The gold-splattered variegated varieties are the most popular but I have always found them difficult to grow. Not so the plain green "Serratifolia." Aucubas are as slow as a freight train so don't expect a big shrub for many years.
If you need one more big shrub to round out your shade planting, try Pittosporum tobira "Variegata," a two-toned shrub that is tough as nails though in two years it will grow to six feet and can grow to 15 feet. Pruning will keep them smaller. The cream-splashed leaves look like shafts of sunlight in the shade. "Wheeler's Dwarf" is a green-leaved pittosporum that also takes shade and grows to about four or five feet tops.