Conifers are defined as a tree that bears cones and needlelike or scale like leaves. The forests of the Pacific Northwest contain more conifers than almost anywhere in the United Sates. Just as all plants grow best when they live in the environment, they are most suited for – cactus in the desert, grasses in the plains – tall, green firs and cedars prefer our cool, wet winters and moderate summers.
The Smith Mossman Western Azalea Garden has a collection of firs but not all are tall or green. Most of the garden is shaded by our native Douglas fir (Pseudotsuga menziesii), which commonly grows 13-24 inches per year for a total height of 195-245 feet. But then you can find Pseudotsuga menziesii ‘Elf’ which only grows one inch a year. And while most Douglas firs are green the Smith Mossman garden includes Pseudotsuga menziesii ‘Hillside Gold’ which has glossy green needles that turn to gold in the winter. Then there’s P. menziesii ‘Seattle Mountain’ that isn’t tall – it only gets to 5 feet tall in 10 years and isn’t green – it has lemon-yellow foliage. All in all, the garden features 13 different cultivars of Douglas firs. And did you know that Douglas fir seeds are an extremely important food for small mammals. Mice, voles, shrews, and chipmunks consume the seeds of the Douglas fir as do many seed-eating birds such as sparrows, juncos and finches.
The Smith Mossman garden also has Western Red Cedar (Thuja plicata), a native to western North America, and its cultivars. In its native habitat, the Western Red Cedar can reach 100-200 feet tall and live from 400 to 1000+ years. Thuja plicata ‘Nana’ and T. plicata ‘Grune Kugel’ only reach between 3 and 6 feet.
Many of the conifers in the Smith Mossman garden are dwarf conifers which may start out as a witch’s broom – a dense mass of shoots emanating from a single point that resemble a witch’s broom. Witch’s brooms are spontaneous mutations and their origins are not completely understood, but may arise from viruses, insects, climatic conditions or a combination of some or all of the above.