Arborvitae, known also as thuja and white cedar, is a species of evergreen tree or large shrub with a distinctive scaly foliage that grows in flat wing shapes, and a craggy bark surface covering the trunk. Many arborvitae cultivars have a tall, upright, almost columnar growth habit though there are more rounded cultivars. Unlike many evergreens, arborvitae is especially sensitive to drought and prefers moist to nearly wet growing soil. It is fast growing and low maintenance, making it a desired landscape plant.
Planting Site Selection & Season
Choose a location to plant your arborvitae that affords full sun or light shade exposure daily. Refrain from planting arborvitae in densely shaded areas as it will stretch to reach the sunlight, becoming thin and leggy. Allow at least 10 feet of planting space between multiple arborvitae trees and more space for the largest cultivars--up to 30 feet. Allow at least 40 feet of overhead clearance from roof lines and utility wires to accommodate the larger trees at maturity. Plant arborvitae in your garden during any of the four seasons where it is winter hardy, ranging from USDA zone 3b through zone 10.
Soil Preferences & Amendments
Provide a nutrient rich and well drained soil that can hold moisture but not trap it to the extent that it pools in the soil. Clay soil is tolerated as are alkaline and acidic soils. Amending the planting bed or top dressing annually with several pounds of well-aged livestock manure and good quality compost will build the soil quality and support the tree's nutritional requirements. Feed arborvitae a few weeks after planting and once or twice per year as needed thereafter with a slow release, high nitrogen lawn fertilizer with something like a 29-3-4 guaranteed analysis. Apply according to label dosing directions, keeping the fertilizer away from the trunk and watering deeply after application.
Planting Depth & Watering
Measure the depth of the nursery container or burlap-wrapped root ball and dig a planting hole that is at least twice the diameter and a foot or so deeper than the root ball it self. Till up the soil in the bottom and sides of the hole so that is is light and loose, so new roots will easily be able to penetrate it. Amend the bottom of the hole with compost and aged manure. Set the arborvitae in the hole and add soil, as needed, under the root ball to bring the top of the root ball level with the surrounding soil. Fill in more amended soil around the root ball and create a 3 to 4 inch high watering moat with the remaining soil. Fill the moat at least twice at planting, allowing the water to percolate down between refillings. Keep the soil evenly moist to very moist for at least two to three months until the tree has established new roots in the soil.