Thuja occidentalis 'Degroot's Spire'

'Degroot's Spire' is a dwarf cultivar of the evergreen, conifer named American arborvitae or eastern arborvitae. It is a compact and slow-growing small tree or large shrub with a narrow conical habit. The leaves are flat, twisted sprays of scale-like rich green foliage and have a citrus or fruity fragrance. It is the perfect evergreen for small vertical spaces in the garden. Pruning of its side shoots when the plant is young may be necessary to maintain its narrow habit. It is a member of the Cupressaceae or cypress family.

The genus name, Thuja, is Greek and is the name of a type of juniper. The species name, occidentalis, means of the "western world." The cultivar is named for Constant DeGroot, who was propagation and production manager for a nursery in Toronto, Ontario, Canada. The plant was first introduced in 1980.

'Degroot's Spire' grows best in full sun to partial shade and loamy, moist, well-drained soils. It prefers acidic to neutral soils.  Mulching is required to maintain moisture at the plant's roots. The plant is intolerant to dry conditions and should be planted in sheltered sites to prevent exposure to winter elements and wind damage. This plant is susceptible to damage from snow and ice. The foliage may turn yellowish-brown or greenish-brown from cold exposure.

It is tolerant of clay soil, air pollution, and black walnut. Pruning should be completed in the early spring before the new growth appears.

Consider Degroot's Spire' as a specimen, accent, container, or patio planting. It serves well as a foundation planting or shrub border. This evergreen would add winter interest to a cottage or rock garden. Wear gloves and protective clothing when handling this plant. The foliage may cause some skin irritation.

Seasons of Interest:

Foliage: Spring, Summer, Fall, and Winter

Quick ID Hints:

• majestic, dwarf, slow-growing, upright, pyramidal habit
• twisted, feathery-sprays, scale-like, medium green foliage
• foliage fragrance of citrus when leaves are crushed or bruised

Pests, Diseases, and Other Plant Problems: 'DeGroot's Spire' has no serious insect or disease problems. Spider mites, leaf miners, bagworms, mealybug, and scale may be seen. Leaf blight will cause spotting of the foliage and leaf drop. It may also be affected by canker.

VIDEO created by Andy Pulte for “Landscape Plant Identification, Taxonomy and Morphology” a plant identification course offered by the Department of Plant Sciences, University of Tennessee.