Northwest Natives as Companion Plants: A Starter Kit
Reprinted from the Rhody Runner, April and May, 1991, the newsletter of the Tualatin Valley Chapter.
One View by Bob Rose
Once the rhododendrons have been selected, it is time to look to other genera to keep them company. Without leaving the heath family, Ericaceae, a gardener can fill many of the spaces with Northwest natives.
At first glance - even at second glance - the ledums look very much like small lepidote rhododendrons. Ledum groenlandicum, shrub from 3'-5' tall, has revolute leaves with brown hairs on the bottom. The flowers, in trusses, are creamy-white, typically open bells and about ¼" in diameter. L. glandulosum has flat, oval leaves, and similar blooms. Both flower in early summer, preferring semi-shade and a moist site. (Ed. Note: All species of Ledum have been placed within the genus Rhododendron by Dr. Walter Judd and Dr. Katherine Kron. Journal ARS, Spring 1991.)
Liking similar moist spots is Leucothoe davisiae. It bears clusters of flowers held above the foliage, pendant white bells. The leaves are leathery, dark green ovals and the plant has a broad fountain growth habit, lt will colonize by stolons over a considerable area.
There are many similarities between this plant and salal, Gaultheria shallon. The leaves of salal are larger and the flowers typically have a pink blush. It has a wide tolerance for growing conditions, taking deep shade or open sunny areas with good moisture. In the shade it may reach 12', but is usually no more than 3'-4' in the sun.
Two other gaultherias, Gaultheria ovatifolia and G. humifusa, make fine ground cover plants in shady sites. They can be difficult to establish, but nursery-grown plants usually will do well in a peaty soil. They are prostrate, with ¼" evergreen leaves, tiny bell flowers and ½" fruits.
Several native vacciniums are fine additions to a semi-shady garden. The evergreen huckleberry, Vaccinium ovaturn, will grow to 4'-6'; it has shiny, almost round leaves and white bell flowers in late spring. The blue-black fruits are delicious, both to people and birds. There is much difference in the fruiting of the plants and if huckleberry pies are a goal, it is a good idea to select heavy-bearing clones. V. deliciosum is the deciduous huckleberry which attracts bears and people for miles around in the fall. Many of these plants fruit so heavily that the branches can be stripped into buckets.
The tall, sparse form of V. parvifolium, the red huckleberry, brings a completely different look into the garden. Its little deciduous leaves are apple-green and the twigs and branches are almost the same color. In the winter the plants are open networks of spring-color. The tasty red berries are borne sparsely, so that getting enough to eat is difficult, but they make the shrub look as though it were decorated for Christmas in the summer.
A gardener who likes a challenge might try the Northwest heather-lookalikes, Phyllodoce empetriformis, P. glanduiiflora and Cassiope mertensiana. The phyllodoces have foliage similar to P. Erica, short, dark green needles. P. empetriformis bears clusters of pink bells and P. glanduliflora has creamy yellow urn-shaped blooms. The Cassiope looks much like Calluna with overlapping scale-like leaves, but its white bells in clusters of 3 to 5 are markedly different from Calluna. All three of these species need peaty-sandy soil in raised beds with open exposure. They may do well in rock gardens along with alpine species of rhododendron.
Some of these Northwest natives are easily available and others may take some searching and time to propagate, but they are all worth the time and the space we may give them. They will enhance the gardens they live in.
Another View by Clarence Smith
I have no quarrel with Bob Ross's selections of rhododendron companions, but feel compelled to nominate five of my own.
Arbutus unedo, or Kilarney strawberry tree, is a miniature cousin of our native Arbutus menziesii or madrona. A. unedo grows to 30'-35' maximum, but is more often seen at half that size. It is a broad-leaf evergreen with bright green pointed leaves about 1" by 3". It blooms in late fall with abundant clusters of creamy white bell-shaped flowers similar to Pieris japonica or madrona. The "strawberry" fruits develop the following summer and persist through fall and winter with the new flowers. I purchased my first A. unedo five years ago and immediately tried some cuttings. All three struck readily. I also tried some seed and found them easy to grow. Now we have lots of them!
The aforementioned Pieris japonica, or Lily of the Valley bush, has a smaller leaf, is also evergreen, and grows to 9', but 5' or 6' is more usual. Its clusters of attractive buds tantalize all winter, then burst open at the first hint of warm weather, often in February. It likes the same soil and growing conditions as rhododendrons. I salvaged my plant from a building expansion project 13 years ago. At 25 years of age, it has been moved three times in the last 13 years and is healthy now after quite a struggle.
The first time I saw Garry a elliptica, the tassel bush, I said to myself, "I must have one of those." (I find myself saying that about too many plants.) It will grow to about the same size as the Arbutus unedo and has similar sized evergreen leaves, but elliptical in shape and a darker green. I tried cuttings several times and finally succeeded with three that are now 2 years old. I'm looking for a well-protected place in my garden as they come from California and Southwest Oregon and are a little tender. At maturity male plants will produce 9" showy white tassles in the spring. I can hardly wait. In the meantime the foliage is worth the effort.
In order to add some midsummer color after the rhododendrons are deadheaded, we added hardy lilies. They grow to 2'-5' and put on spectacular flowers in June, July and August. Many are fragrant and they come in many colors. We have one hybridized by Lloyd Baron that grows to 8' and has flower size to match. They're fun and they're easy.
And to fill all those little spaces in between, we are finding Penstemon in its many species and hybrids make marvelous ground covers and provide exciting bloom all summer. Usually pink, blue, lavender or violet, sometimes white, they come in all sizes and shapes. The Northwest has many varieties growing on rocky hillsides in the high mountains. They start easily from cuttings or seed and are fun to collect.
So now there are 10, and I'll bet many of you have another five you could add to the 'Companion Plants for Rhododendrons Starter Kit.'