The Green Giant Arborvitae, a fast-growing hybrid of western red cedar and Japanese arborvitae, is a popular choice for creating dense privacy screens and windbreaks. This robust evergreen is valued for its rapid growth rate, which can reach three to five feet per year once established. Successfully integrating this plant depends significantly on selecting the correct time for planting, as timing directly influences root establishment and the tree’s long-term health.
Identifying the Ideal Planting Windows
The most advantageous times for planting Green Giant Arborvitae align with periods of moderate temperatures, which promote root development while minimizing stress on the foliage. There are two distinct windows that offer optimal conditions for establishment. The first opportunity occurs in the early spring, immediately after the threat of the last hard frost has passed.
Planting in early spring allows the tree to benefit from the soil’s increasing warmth, which stimulates active root growth before the onset of summer’s intense heat and potential drought conditions. A well-established root system ensures the tree has a full growing season to acclimate before the ground cools again. This timing is particularly beneficial in regions with very hot summers where the young tree would otherwise struggle to manage water loss through its foliage.
The second effective period for planting is the early fall, ideally at least six to eight weeks before the ground is expected to freeze solid. During this time, air temperatures are cooler, reducing water evaporation and lessening the risk of transplant shock. Although the air is cool, the soil retains warmth from the summer, creating an environment suited for root expansion and deep establishment. This fall planting allows the Green Giant to focus on subterranean growth throughout the cooler months, setting it up for robust top growth the following spring. Conversely, planting in mid-summer or mid-winter is discouraged due to immediate heat/drought stress or frozen ground preventing root growth.
Essential Soil and Site Preparation
Green Giant Arborvitae perform best when situated in a location that receives full sun, defined as a minimum of six hours of direct sunlight per day. They can tolerate partial shade, which may include light afternoon shade, particularly in hotter climates where protection from intense midday sun is beneficial.
The tree requires well-draining soil to prevent waterlogging, which can lead to root rot. While adaptable to a range of soil types, including some clay and sand, it thrives in moist, fertile, loamy soil. The ideal soil pH should be slightly acidic to neutral, generally falling within a range of 5.5 to 7.0.
Assess the soil’s drainage before committing to a site by digging a small test hole and observing how quickly water percolates. If the soil is compacted or drains poorly, incorporating organic matter like compost or well-aged manure can significantly improve the soil structure and aeration. This preparation minimizes the chance of fungal diseases and maximizes nutrient uptake.
Step-by-Step Planting Process
The planting hole should be dug two to three times wider than the diameter of the root ball, but only as deep as the root ball itself. A wider hole allows the newly forming roots to easily spread into the loosened surrounding soil, promoting faster establishment.
Before placing the tree, the root ball should be inspected and prepared by gently loosening or scoring the outer roots, especially if they are tightly circling the container. This action encourages the roots to grow outward into the native soil. The tree must be positioned so that the root flare, the point where the trunk widens at the base, sits level with or slightly above the surrounding grade. Planting the tree too deeply is a common error that can lead to stem rot and suffocation of the roots.
The hole should be backfilled with the original soil that was removed, avoiding excessive soil amendments, which can discourage roots from venturing outside the planting zone. As the hole is filled, the soil should be gently tamped down to eliminate any large air pockets that can dry out the roots.
Critical Care Immediately After Planting
The most immediate step after backfilling the hole is to provide a deep, thorough initial watering to settle the soil and fully saturate the root zone. This soaking helps remove any remaining small air pockets and minimizes transplant shock. For the first year, a consistent watering schedule is necessary for root establishment, especially during dry spells and the heat of summer.
While the specific frequency depends on climate and soil type, a general guideline is to water deeply one to three times per week, ensuring the soil remains moist but never soggy. The goal is to encourage the roots to grow deep into the ground rather than remaining near the surface. Applying a layer of organic mulch, such as shredded bark or wood chips, is highly beneficial.
The mulch should be spread three to six inches deep across the planting area, extending outward as far as the canopy permits, but it must be kept several inches away from the trunk. This practice conserves soil moisture, moderates soil temperature, and suppresses competing weeds. Staking is generally unnecessary, but temporary staking for the first year may be used in exposed, windy locations to prevent root rock, provided the ties are flexible and not constricting.