Thuja — 15 species

Thuja is a genus of coniferous evergreen trees and large shrubs — including Arborvitae, Western Red Cedar, Chinese Arborvitae, and Japanese Arborvitae — widely used for hedging, screening, and specimen planting. They are sun-lovers requiring full to partial sun and regular watering when young, settling to about half an inch per week once established; good drainage is essential as they dislike waterlogged roots. Toxicity varies across the genus: the essential oils, particularly thujone concentrated in foliage, cones, and wood, can cause vomiting, drooling, and neurological signs in pets, but sensitivity differs by species, so verify the safety of each specific Thuja before planting in a garden frequented by cats or dogs.