Just as the crown of a Green Giant arborvitae (Thuja plicata "Green Giant") grows up to 20 feet in diameter, the root system spreads underground. The roots of all trees are designed for drawing nutrient-rich water from the ground. However, the Green Giant's roots also spread wide supporting the 60-foot tree against winds and snow.
One of the most helpful aspects of the Green Giant's root system is its strength. Roots from this tree unfold both deep and wide, allowing the tree to stand up to extremely high winds as well as hold heavy loads of snow without toppling. Green Giant, unlike other large trees, do not feature roots above ground but grow all their roots below ground. This helps prevent burning or drying during long periods of drought and freezing from heavy snow. Deep-growing and wide-spanning roots help this tree remain green all year and reach heights of up to 60 feet or more.
Although the roots of all plants seek water and nutrients in whatever soil they are placed, some soils are better than others are for certain plants. The Green Giant grows in several soil types but prefers moist, well-draining soil with a high degree of fertilizing elements, such as nitrogen, phosphorus and potassium. Soil such as loam works better than sandy or clay soil and drains better than peat soil. A fast grower, the Green Giant's roots consume a large quantity of nutrients, and the plant must remain well fertilized.
Susceptible to Rot
Especially pervasive in poorly draining soils, arborvitae roots are more susceptible than others to root rot. A mildewlike soilborne infection washes into the root system through water causes this infection. The roots are at once deprived of necessary oxygen and fed upon by the mold that breaks the roots down into grimy sludge. If root rot is not treated, arborvitae withers and dies.
Green Giant propagates not only through cones, but also through cuttings taken from the root. This method used by horticulturalists creates a genetically identical copy of the tree from which it was cut.