The Pacific dogwood (Cornus nuttallii), also called California dogwood tree, Western dogwood and mountain dogwood is a species of dogwood tree native to western North America often grown as an ornamental tree in coastal regions west of the Cascades.
This tree was first described by Scottish botanist David Douglas during his expedition to the Pacific Northwest in the 1820s, where he mistook it for C. florida and did not send seeds back to England. However, it was English botanist Thomas Nuttall who was the first to describe the species for science while staying at Fort Vancouver in the autumn of 1834. The tree’s name used by Hul’q’umi’num’-speaking nations is Kwi’txulhp.
The Pacific Dogwood was adopted as the official floral emblem of British Columbia in 1956, and a law was passed that prohibited any part of the tree from being dug up or cut down. However, this law was repealed in 2002. The species name nuttallii was given in honor of Thomas Nuttall (1798-1859), a British-born botanist and ornithologist.
This tree grows to a height of 20-30 feet, but can reach up to 90 feet under optimal conditions. It has a moderate growth rate, adding about 1 foot per year until it reaches maturity. The tree can live to be 150 years old, but its lifespan is usually shorter due to susceptibility to dogwood anthracnose, a disease caused by the fungus Discula destructiva.
The leaves of the Pacific Dogwood are opposite, clustered at the ends of branches and simple. The leaves are elliptic-ovate to obovate. They are wedge-shaped at the base and usually have a short point at the apex. Each leaf has pairs of veins, and the petiole is relatively long. In the fall, the leaves of the Pacific Dogwood take on shades of purple and red. The young bark is thin and smooth, but as the tree ages, it develops ridges that give the trunk a “scale-like” appearance. This bark is a rich brown color.
The tree has white bracts that surround the small, inconspicuous flowers, creating the appearance of larger flowers. The flowers themselves are individually small and inconspicuous, produced in a dense, rounded, greenish-white flower head. The large white ‘petals’ are actually, creating the appearance of a larger flower head. It flowers in April or May, before its leaves are out.
The fruit of the Pacific Dogwood is a small, bright red drupe that contains several seeds. The fruit is not eaten by humans, only birds and wildlife feed on the fruit. The fruit is similar to that of the Eastern Flowering Dogwood (Cornus florida), but it is more closely packed and produces more fruits per cluster. The fruit is described as a drupe, which is a fleshy fruit with one hard-shelled seed, with the fruit not splitting open when mature. However, sometimes a fruit may contain two seeds, making it a berry.
The Pacific Dogwood prefers moist, well-drained soils that are high in organic matter. It can grow in a variety of soil types, from clay to sandy loam, and prefers acidic soils with a pH between 5.5 and 6. It is present in all stages of both primary and secondary succession, from new colonization to climax communities. The tree’s habit varies depending on sunlight exposure. In full sun, it has a short trunk with a crown as wide as it is tall. Under a canopy, it develops a tapered trunk with a short, slender crown.
Cultivation of Pacific Dogwood
Planting
- Fall or early spring are ideal for planting when the Pacific Dogwood is dormant. This allows root establishment before summer heat.
- Choose a location with partial shade to full sun. Pacific Dogwoods can tolerate full sun if the soil remains moist. Ensure the site has well-drained, acidic to neutral soil rich in organic matter.
- Amend the soil with compost or well-rotted manure to improve fertility and drainage. Test the soil pH and adjust if necessary to maintain a slightly acidic to neutral range (pH 6.0-7.0).
- Dig a hole 2-3 times wider than the root ball and just as deep. Loosen the soil around the edges to encourage root growth. Place the tree in the hole, ensuring the root flare (where the roots meet the trunk) is level with the soil surface. Backfill with the amended soil, gently firming it around the roots to eliminate air pockets.
Care
- Water regularly, especially during the first two years to establish the root system. After establishment, water during dry periods.
- Apply a 2-3 inch layer of mulch around the base, keeping it a few inches away from the trunk to prevent rot. Mulch helps retain moisture, regulate soil temperature, and suppress weeds. Replenish mulch as needed.
- Fertilizing may not be necessary if the soil is rich in organic matter. However, if the tree shows signs of struggle (pale leaves, stunted growth), a balanced fertilizer applied in early spring can be beneficial.
- Prune in late fall or winter when the tree is dormant. Remove dead, diseased, or damaged branches. Thin out crowded branches to improve air circulation.
- Protect young trees from frost and harsh winter winds by wrapping them in burlap or using a tree guard.
Pests and Diseases
- Dogwood Anthracnose: This fungal disease causes leaf spots, twig dieback, and can be fatal. Ensure proper spacing, improve air circulation, and avoid overhead watering to reduce the risk.
- Powdery Mildew: Another common issue, which can be managed by ensuring good air circulation and using fungicides if necessary.
- Insect Pests: Watch for aphids, scale, and borers. Treat infestations with insecticidal soap or horticultural oil.