Arborvitaes Tree

Thuja is a genus of evergreen conifers that includes trees and a few shrubs. Its species are typically dense, with flattened sprays of scale-like leaves and small cones, but mature size, crown shape, and foliage color vary among species and cultivars. [Oregon State University](https://landscapeplants.oregonstate.edu/thuja) describes the genus and its Cupressaceae family. ## Form and garden use Depending on the selection, Thuja can form a narrow column, a broad pyramid, or a rounded mound. Arborvitaes are used for screens, hedges, shelter plantings, and as specimen plants; cultivar choice matters because size, habit, and winter foliage color vary. [Iowa State University Extension](https://yardandgarden.extension.iastate.edu/article/2004/6-25-2004/arborvitae.html) describes common landscape roles for the widely planted eastern white cedar, while Oregon State notes the broader range of Thuja forms. ## Growing conditions Growing requirements depend on the species and cultivar. Many landscape arborvitaes grow in moist, well-drained soil and in sun or partial shade, but check the individual selection’s hardiness and mature spread before planting. ## Maintenance Water newly planted trees and shrubs while they establish. Keep enough room for the selected plant’s mature size, and prune only when the cultivar or planting design calls for it. The 2025 Yavapai County guide lists Thuja at genus scope among fire-prone plants. This is a fire-hazard warning, not an individual assessment of every species or cultivar. Follow the guide's placement and maintenance guidance. ## FireSmart BC hazard warning [FireSmart BC](https://firesmartbc.ca/landscaping-hub/fire-resistant-plants/#fire-hazards) lists Thuja as Highest Risk in its fire hazard table. This is a broad genus-level warning, not an individual assessment of every species or cultivar; follow local placement and maintenance guidance. ## Yavapai County — 2025 source scope and care The [University of Arizona Yavapai County bulletin](https://extension.arizona.edu/sites/default/files/2025-03/FirewisePlants3-14-2025.pdf), page 3, lists Arborvitae with the botanical cell Thuja, Platycladus and form T, S. It places this entry in its fire-prone list. The matched catalog name is Thuja. The printed arborvitae row names both Thuja and Platycladus. The Thuja genus record and unselected Platycladus orientalis are separate representatives; no named cultivar is independently assessed. Source form codes: C=groundcover, G=grass, P=perennial, S=shrub, T=tree and V=vine. Printed names and form codes can include source spelling errors or historical taxonomic treatments; the source wording is retained separately from the catalog name and plant-specific habit. The bulletin warns that fire-prone plants can ignite readily and burn intensely, and should be removed or aggressively maintained when near a home, road or driveway. For native trees it calls for removing dead material, keeping limbs out of the lower 6–10 feet and clearing shrubs beneath the canopy. For other fire-prone natives it calls for isolated stands more than 30 feet from structures. Apply current local requirements and pruning suited to the identified plant. No plant is fireproof. Keep this Yavapai classification separate from Arizona UA, Utah, New Mexico, Idaho, Colorado and other source ratings and their placement, moisture and maintenance conditions.