Green Giant Arborvitae Fertilization: Timing, Rate, and Herbicide Warning

Owner asks what fertilizer to use for newly planted Green Giant arborvitae (Thuja 'Green Giant').

Fertilizer Recommendation

• Product: 10-10-10 balanced fertilizer
• Rate: 1 lb per inch trunk diameter
• Method: Scatter evenly to drip line, water in (or before rain)
• Timing: Spring and mid-summer
• First year: Do NOT fertilize—let roots establish

Critical Warning: Avoid Weed & Feed

Never use lawn fertilizers containing herbicides (e.g., "Weed & Feed," crabgrass preventers). These contain broadleaf herbicides (2,4-D, dicamba) that kill trees when roots absorb them. Arborvitae are highly sensitive.

Alternative: Slow-Release Tree Spikes

Acceptable for small trees if granular isn't practical. More expensive, slower release, but safer than herbicide-contaminated products.