Green Giant Arborvitae (Thuja x ‘Green Giant’) is a popular evergreen, known for its rapid growth and dense, conical shape, making it ideal for privacy screens and landscape accents. Maintaining their health and deep green foliage often depends on proper nutrient availability. Fertilization supports robust growth, especially in soils lacking essential nutrients.
When to Fertilize Green Giant Arborvitae
The optimal time to fertilize Green Giant Arborvitae is in early spring, just before new growth begins. This allows the plant to absorb nutrients as it prepares for active development. Applying fertilizer at this point supports new foliage emergence and root system expansion. For newly planted arborvitae, it is recommended to wait until their second growing season before fertilizing, allowing them to establish their root systems.
A secondary, lighter application can be considered in late fall, after the first hard frost but before the ground freezes. This late-season feeding supports root development and carbohydrate storage, helping the tree withstand winter and prepare for spring growth. However, the primary focus for nutrient application remains the early spring period to fuel the most significant growth spurt.
Selecting the Best Fertilizer
When choosing a fertilizer for Green Giant Arborvitae, consider the NPK ratio. NPK stands for nitrogen (N), phosphorus (P), and potassium (K), the three primary macronutrients plants require. A balanced fertilizer, such as a 10-10-10 or 12-12-12, is a suitable choice for general health. Alternatively, a formula with higher nitrogen, like a 20-5-10, can support lush, green foliage.
Slow-release granular fertilizers are preferred for arborvitae because they provide a steady supply of nutrients over an extended period. This reduces the risk of nutrient burn and minimizes frequent applications. Quick-release liquid fertilizers offer immediate nutrient availability, useful for correcting specific deficiencies, but require careful application to avoid over-fertilization. Fertilizers formulated for evergreens, trees, and shrubs often contain the appropriate nutrient balance.
Step-by-Step Fertilization Process
Before applying any fertilizer, thoroughly water the Green Giant Arborvitae. This protects roots from potential fertilizer burn and ensures moist soil for nutrient absorption. For granular fertilizers, measure the amount based on product instructions, often specified per tree height or caliper. Distribute granules evenly around the tree’s drip line, the area directly beneath the outermost branches. Avoid placing granules directly against the trunk to prevent damage.
After spreading granular fertilizer, lightly rake it into the top inch or two of the soil. This incorporates the fertilizer and prevents wash-away. Follow with another thorough watering to dissolve nutrients and move them into the root zone. If using liquid fertilizer, dilute it according to product instructions, as concentrations vary. Apply the diluted solution to the soil around the tree’s base, ensuring the root zone is adequately drenched.
Consistent watering after fertilization is important. This transports nutrients to the root system for absorption. Always adhere to the specific dosage recommendations on the fertilizer packaging, as these are tailored to the product’s concentration and release rate.
Tips for Successful Fertilization
Always water Green Giant Arborvitae deeply both before and immediately after applying fertilizer. This prevents root damage from concentrated nutrients and helps move nutrients into the soil. Avoid over-fertilization, as it can lead to nutrient burn, evidenced by browning or yellowing foliage, and harm the tree’s long-term health.
Do not fertilize Green Giant Arborvitae stressed from drought, disease, or recent transplanting. These trees need to recover before additional nutrient inputs. A soil test provides precise information about existing nutrient levels and pH, allowing for a targeted fertilization approach. Monitoring the tree for signs of nutrient deficiencies, such as stunted growth or discolored leaves, also helps determine if fertilization is necessary. Avoid fertilizing too late in the growing season, after late summer, as this can promote tender new growth vulnerable to early frost damage.