Lawson’s cypress (*Chamaecyparis lawsoniana*) is an evergreen tree that can grow to 61 m tall and 1.2 to 2 m wide. It can live for hundreds of years. The cedar wood is one of the most valuable harvested woods in North America. Female seed cones develop in spring and mature to a brown color.
I. Appearance and Characteristics
Chamaecyparis lawsoniana, known as Port Orford cedar or Lawson cypress, is a species of conifer in the genus Chamaecyparis, family Cupressaceae. It is native to Oregon and northwestern California, and grows from sea level up to 4,900 feet (1,500 m) in the valleys of the Klamath Mountains, often along streams.
A large evergreen tree, specimens mature up to 200 ft (61 m) tall or more, with trunks 4–7 ft (1.2–2 m) in diameter, exceptionally 8–9 ft (2.4–2.7 m). The bark is silver-brown, vertically furrowed, and 6–10 inches (15–25 cm) thick near the base. The foliage is arranged in lacy, flat sprays with a feathery appearance, usually somewhat glaucous (i.e. blue-green) in color. The leaves are scale-like, 1⁄8–3⁄16 inch (3–5 mm) long, with narrow white markings on the underside, and produced on somewhat flattened shoots. The foliage gives off a rather pungent scent, not unlike parsley.
The seed cones are globose, 9⁄32–9⁄16 inch (7–14 mm) in diameter, with 6–10 scales, green at first, maturing brown in early fall, 6–8 months after pollination. The male cones are 1⁄8–5⁄32 inch (3–4 mm) long, dark red, turning brown after pollen release in early spring. The seeds fall quickly and can float on water.
Old specimens lack branches near the base and often have dead tops. They can live up to about 600 years of age.
Lawson’s cypress is completely inedible, and generally, humans don’t try to eat it. However, the foliage can irritate the skin of sensitive people, causing a rash. If the foliage is eaten, it will irritate the inside of the mouth, the throat, and the digestive tract in the same way. Keep small children away from this tree. If you need to prune it or handle the foliage, wear gloves and protective clothing.
The species was first discovered (by European Americans) near Port Orford, Oregon, and introduced into cultivation in 1854 by collectors working for Charles Lawson FRSE of the Lawson & Son nursery in Edinburgh, Scotland, after whom it was named as Lawson Cypress by the describing botanist Andrew Murray. The United States Department of Agriculture officially calls it by the name Port Orford cedar, as do most people in its native area, but some botanists prefer to use the name Lawson cypress (or in very rare instances Port Orford cypress) instead. The name “Lawson’s cypress” is widely used in horticulture.
II. How to Grow and Care
Sunlight
Lawson’s cypress thrives in conditions of full sun, where it receives unfiltered light for at least 6 hours a day. Its growth and health are highly dependent on adequate light exposure, which fuels photosynthesis and maintains the lush, green coloration of its foliage. Though lawson’s cypress is tolerant of partial sun, receiving 4 to 6 hours of direct light, lower light levels may result in reduced vigor and sparse, leggy growth. In shade, lawson’s cypress could experience stunted development. Ideally, these plants should be placed outdoors where they can bask in ample light to ensure robust structure and optimal health.
Watering
Originating from the moist forests of North America, lawson’s cypress thrives in environments with consistent humidity. It has adapted to withstand periods of relative dryness, showing a preference for moderate moisture levels without being overly demanding. For optimal health, lawson’s cypress should be watered once every 1-2 weeks, allowing the soil to dry slightly between watering sessions. As an evergreen plant, lawson’s cypress maintains its foliage year-round, which can influence its water uptake and transpiration rates; thus, ensuring it receives adequate water during its active growth phase is crucial.
Fertilizing
For lawson’s cypress, a balanced nutrition fertilizer ensures optimal growth. Apply a slow-release formula in spring as new growth appears, following package instructions for quantity. This promotes vigor and health. Seasonal adjustments are necessary; decrease frequency in fall as lawson’s cypress prepares for dormancy. Over-fertilizing can cause harm—adhere strictly to recommended amounts.
Tip: water lawson’s cypress before and after applying fertilizer to prevent root burn and aid nutrient uptake.
Propagation
Lawson’s cypress can be propagated through layering, cutting, or sowing seeds, ideally during the autumn and winter months. Successful propagation is indicated by new growth and root development. Patience and a proper environment are essential for successful propagation.
Transplanting
The best time to transplant Lawson’s cypress is from early spring to early summer, when the weather is mild. This allows the plant to establish its root system in the new location. Choose a well-drained site with partial shade for optimal growth. Remember to handle Lawson’s cypress gently during transplant to avoid damaging the roots.
Repotting
When repotting lawson’s cypress, a coniferous tree with a pyramidal shape, choose early spring before the growth cycle. Repot every 2-3 years to accommodate its size. Select a large, deep pot for root development. After repotting, ensure Lawson’s cypress gets ample water and partial shade to avoid stress. A friendly reminder: Lawson’s cypress thrives in well-draining soil and consistent care.
Pests and Diseases
In the wild, the species is seriously and uniquely threatened by a root disease caused by the oomycete pathogen, Phytophthora lateralis, accidentally introduced in the early 1950s following the fungus’s arrival to the Pacific Northwest on nursery trees. This disease is also a problem for horticultural plantings in some parts of North America. The tree is sometimes killed, though less often, by other species of Phytophthora.
Phytophthora lateralis infection begins when mycelium, from a germinated spore, invade the roots. The infection then spreads through the inner bark and cambium around the base of the tree. Spread up the trunk is generally limited. Infected tissue dies and effectively girdles the tree. Large trees are more likely to be infected than small trees due to larger root areas (although all trees at the edges of infected streams will eventually succumb). However, large trees can often live with the infections for a longer duration (up to several years).
C. lawsoniana in streamside populations are highly susceptible to P. lateralis infection. However, the rate of fungal spread through populations in dry upland areas appears to be slow. P. lateralis spreads through water via mobile spores (zoospores). The fungus also produces resting spores (chlamydospores) that can persist in soil for a long period of time. New infections generally begin when soil is transferred from an infected population to a non-infected population via water, human or animal movement. After initial infection in streamside populations, secondary spread via zoospores quickly infects all downstream individuals.
Human facilitated spread is thought to be responsible for most new, and all long-distance, infections. Soil on vehicle tires, especially logging trucks and other off-road vehicles, is considered the most pressing problem due to the volume of soil that can be carried and the traffic rate in and between susceptible areas. Spread on boots and mountain bike tires has also been suggested and probably contributes to new infections locally. Animal-facilitated spread is thought to occur, but is localized.
The United States Forest Service and Bureau of Land Management attempt to prevent Phytophthora spread through road closures, monitoring, research and education. Research has focused on determining the dynamics and mechanisms of spread, as well as attempts to breed resistant trees. One solution against Phytophtera is known generically as Mancozeb and also commercially known as Dithane (C). Commercial preparations of the parasitic fungus Pythium oligandrum are licensed for pest control, and documented to predate many species of Phytophthora.
III. Uses and Benefits
The species was discovered by Euro-Americans in the 1850s. The wood is light yet has great strength and rot resistance, even after long exposure to salt water. Its properties resemble those of yellow-cedar, but was historically more available in the region. On shores lacking docks, logs were transported via high-line cable directly onto ship decks. It was valued for boatbuilding. The species was important to Oregon’s lumber industry until the 1950s when it was crippled by disease. It was preferred for storage battery cell separation, Venetian blinds, and other uses. Quality specimens eventually began to be shipped almost exclusively to East Asia, where it is highly valued. Large amounts have been exported to Japan where it is used in making coffins, shrines, and temples. Its lumber is known for its highly fragrant ginger aroma, caused by an oil which repulses decay and insects, including termites; this oil has been used as an insecticide. Due to the straightness of its grain, it is also one of the preferred woods for the manufacture of arrow shafts. It is also considered an acceptable, though not ideal, wood for construction of aircraft.
The wood is considered more than acceptable for use in stringed instruments. Its fine grain, good strength and tonal quality are highly regarded for soundboards in guitar making.