Spread a 2 to 4 inch layer of some organic material like chopped leaves, shredded bark or wood chips on the soil under the tree.
Firs appreciate moist soil. They do not normally need supplemental watering except when they are First planted or in the late fall before the ground freezes for the winter. During drought periods, however, when rainfall is scarce, they will need to be watered.
Feed Firs once a year in the fall for the First 3 or 4 years after planting. Sprinkle an all-purpose, slow acting granular fertilizer on the soil under the tree out to 1-1/2 times beyond the tips of the branches (the drip line). Do not let any fertilizer touch the trunk. Use about 1/2 pound of fertilizer for trees with a trunk diameter of 1/2 inch at the base.
Firs don't normally need pruning, as they maintain their distinctive shape very well. Do not prune branches from Firs unless it is necessary to control a pest or disease problem. Because these trees do not replace lost lower limbs, pruning them risks marring the overall shape of the tree.