The fertilizer used for arborvitae should consist of a higher nitrogen concentration than the other nutrients. The first number that appears on the label of the fertilizer should be double the second number, as in 20-10-5 or 12-6-6.
Organic fertilizers that have a high nitrogen concentration include well-rotted manures and compost. When using a chemical fertilizer, only the recommended dosage should be used. Arborvitaes, along with other evergreens, only require annual feedings over the first five years of growth. If an arborvitae displays signs of a nutrient deficiency after the five-year growth period, the surrounding soil should be tested to evaluate the causes.