Green Giant Arborvitae (Thuja plicata ‘Green Giant’) is a popular evergreen, widely used for privacy screens and dense hedges. This fast-growing conifer forms a natural barrier, reaching impressive heights and widths quickly. Its hardiness and adaptability make it suitable for various climates, providing year-round green foliage.
Planting and Establishment
Successful growth of Green Giant Arborvitae begins with proper site selection. These trees thrive in full sun to partial shade, ideally with at least six hours of direct sunlight daily for optimal growth. Well-draining soil is important to prevent root issues, though Green Giants tolerate a range of soil types. They do not perform well in consistently wet or poorly drained conditions.
Dig a hole twice as wide as the root ball but only as deep. Position the top of the root ball level with or slightly above the surrounding ground for proper drainage and root health. Do not amend the soil around the planting hole, as this encourages roots to stay within the amended area rather than extending into native soil. After placing the tree, backfill the hole, gently tamp the soil to remove air pockets, and water thoroughly.
Consistent watering is essential during the first year of establishment. Newly planted Green Giants require regular moisture to develop a strong root system. Provide about one inch of water per week, from rainfall or supplemental irrigation, ensuring the soil remains moist but not waterlogged. Maintaining a layer of mulch around the base, kept a few inches from the trunk, helps conserve soil moisture and regulate temperature.
Ongoing Care Essentials
Once established, Green Giant Arborvitae are relatively low-maintenance. Mature trees require less frequent watering than newly planted ones, but deep watering is beneficial during dry periods or extended heat. Watering deeply encourages roots to grow downward, making the tree more drought-tolerant.
Fertilization is not always necessary, especially if trees are growing vigorously in healthy soil. If growth appears slow or foliage lacks vibrancy, apply a balanced, slow-release fertilizer in spring to promote new growth. Avoid over-fertilization, as it can harm the roots. A nitrogen-rich fertilizer encourages healthy green foliage.
Pruning is minimal, usually limited to shaping or removing dead or damaged branches. Light trimming for shaping can be done any time of year, though avoid hot summer months. For significant reductions or heavy shaping, late winter or early spring before new growth emerges is best, as the tree is dormant and recovers well. Avoid removing more than one-third of the plant’s mass at once to prevent stress.
Common Problems and Solutions
Green Giant Arborvitae can encounter several health issues. Browning foliage is often caused by insufficient water, especially in newly planted trees or during drought. It can also result from winter burn, where cold winds and sun desiccate the needles. Root rot, a fungal disease, leads to browning and wilting, occurring in oversaturated or poorly draining soil. Proper watering and soil drainage help prevent these problems.
Pest infestations can affect Green Giants. Bagworms are caterpillars that construct protective bags from needles and debris; severe infestations can cause defoliation and branch dieback. Hand-picking bags before they hatch controls small populations, while biological or chemical treatments may be necessary for larger outbreaks. Spider mites are tiny arachnids that suck sap from needles, causing yellowing or browning and sometimes fine webbing. Horticultural oils or miticides manage mite populations.
Fungal diseases, such as tip blight or canker, can impact Green Giants, leading to discolored needles, branch dieback, or bark lesions. These issues arise in wet conditions or when trees are stressed. Removing infected branches and ensuring good air circulation helps. Proper identification is important before applying any treatment, as symptoms can sometimes overlap.
Winter Protection
Preparing Green Giant Arborvitae for winter, particularly in colder climates, helps protect them from seasonal damage. Ensuring adequate moisture before the ground freezes is effective. Deep watering in late fall allows roots to absorb and store water, mitigating desiccation during dry winter months.
Protection from winter burn, caused by cold, dry winds and bright winter sun, is important. Apply an anti-desiccant spray in late November or early December, when temperatures are above 40 degrees Fahrenheit, to help evergreens retain moisture. For younger or more exposed plants, burlap wraps provide a physical barrier against harsh winter elements.
Managing snow load is also important, as heavy snow or ice can accumulate on branches, leading to breakage. Gently remove heavy snow from branches with a broom to prevent damage. Avoid planting in areas prone to excessive snow accumulation to reduce the risk of structural harm.