Arborvitae (Thuja) are favored evergreen trees often selected for creating dense privacy screens or formal hedges. Valued for their consistent foliage, they provide year-round structure in a landscape. The success and long-term health of a newly planted arborvitae depend significantly on selecting the correct time for installation, which minimizes transplant shock and helps establish a robust root system.
Optimal Seasons for Planting
The most advantageous times to plant arborvitae are during two distinct windows when environmental conditions favor root development. The first period is early Spring, immediately after the ground thaws but before high summer temperatures begin. Planting allows the tree to focus energy on growing new roots throughout the spring and early summer, avoiding the stress of heat and potential drought.
The second optimal period is early Fall, typically from mid-August through October, or six to eight weeks before the first hard frost. Cooler air temperatures reduce water loss through the foliage, lessening transplant shock. The soil remains warm enough to encourage active root growth until the ground freezes, even as foliage growth slows.
Fall planting often provides a slight advantage over Spring. Since the tree is not simultaneously supporting new top growth, it dedicates resources exclusively to root establishment during cooler, moister conditions. This extended root growth better prepares the tree for the following spring’s demands. Moderate temperatures between 40°F and 75°F are necessary for the best outcomes in either season.
Timing Constraints Based on Stock Type
The precise planting dates are heavily influenced by how the tree is supplied by the nursery.
Container and B&B Stock
Container-grown trees and balled and burlapped (B&B) stock offer the greatest flexibility. Since the root ball remains intact and surrounded by soil, these trees can be successfully transplanted anytime during the optimal Spring and Fall windows. The existing soil mass protects the feeder roots, making the transition smoother.
Bare-Root Stock
Bare-root arborvitae impose a much more rigid and narrow planting schedule. These trees are dug while completely dormant, with all soil washed away, and are only available for a short time in late winter or very early Spring. They must be planted immediately upon receipt, ideally within a few days, while the tree is still dormant and before new buds swell.
The exposed root systems of bare-root stock are highly susceptible to drying out. This stock type is only viable when the soil is workable but temperatures remain cold enough to prevent the tree from breaking dormancy. Once the tree begins allocating energy toward leaf development, planting bare-root stock becomes highly risky and unsuccessful.
Environmental Conditions to Avoid
Successful establishment relies on avoiding environmental extremes that cause excessive stress and inhibit root growth. Planting should be avoided during the peak of summer (late June through early August) due to high air temperatures and potential drought. Intense heat increases evapotranspiration, causing water stress and severe transplant shock.
Planting must also be avoided when the ground is deeply frozen, as frozen soil stops all root growth and prevents proper digging. The soil must be thawed and workable, ideally above 40°F. Attempting to plant in waterlogged or oversaturated soil is similarly detrimental, leading to immediate root suffocation and fungal diseases.
Even during ideal seasonal windows, immediate planting should be postponed if severe weather is occurring. Heavy rainfall or high winds can make it difficult to position the tree correctly, lead to water pooling in the planting hole, or damage the fragile canopy. Waiting for a period of calm, mild weather gives the newly planted arborvitae the best chance to settle in.