What type of fertilizer for a red cedar tree?

A lime fertilizer is what is used to fertilize little cedar trees (Cedrus spp).

Specifically, cedar trees favor neutral to slightly acidic soils. Lime-based fertilizers help lower the soil pH to between the 5.5 to 6.5 range beneficial to cedar tree growth. But fertilizer must be applied only in the case of poor quality soils. Otherwise, young cedar trees need most a space that is clear of such shallow-rooted competitors as ferns, grasses and weeds; that is 3 feet (0.9144 meters) away from water bodies; and that receives full sunlight.