Things You'll Need
Liquid lime sulfur
Evergreen trees are any variety of tree that does not shed its needles or leaves during the winter months. Some varieties of evergreen trees include pine, cypress, juniper, hemlock and arborvitae. Caring for evergreen trees is similar to caring for other tree types. It is important to continue care for the evergreen year-round. Even though they may look healthy in the winter months, they still require as much care as they do in the summer.
Water the evergreen tree every 10 to 14 days until the soil is moist to a 6-inch depth.
Spread a 2 to 4-inch layer of mulch, such as peat moss, leaves or grass clippings, around the base of the evergreen tree to prevent the moisture from evaporating from the soil.
Prune the evergreen tree to remove all dead limbs, which are brown or yellow, by cutting them off near the trunk using a pruning saw. Trim the outer foliage of the evergreen with pruning shears to create the desired shape or to reduce the length of limbs. Prune pine trees in July, and prune all other evergreens in early spring before new growth begins to emerge.
Apply a granular fertilizer to the soil above the evergreen tree in the early spring or late fall, only if the foliage starts to yellow. Use 1 tbsp. of a balanced fertilizer, such as 12-12-12, and sprinkle it evenly around the soil at the base of the tree.
Spray the entire evergreen tree in the early spring to kill any insects and larvae that invaded the tree during winter. Apply liquid lime sulfur if it is a yew, fir, Colorado blue spruce or Douglas fir, according to the Wisconsin State University website. Spray all other trees with dormant oil.
Spray arborvitae and spruce evergreens with a direct stream of cold water from a garden hose once per week to eliminate insects.
Do not fertilize the evergreen more than once per year and do not use more than the recommended amount of fertilizer. Excess fertilizing will kill the evergreen.