Arborvitae – Pruning, Winter Care and Fertilizing

These evergreens can be sheared lightly in early spring to improve the plants shape and increase density. The plant should be wider at the base than the top, to allow light to reach the lower branches. “Pick pruning” will extend the useful life of the plant by giving it a deeper “green” zone. This is done by cutting small holes in the surface of the plant, allowing more light in and new buds to form on the inside of the plant.

Young evergreens respond very well to fertilizing. Either granular, liquid or stake type fertilizers can be used. Granular fertilizers can be worked into the soil around the plant at a rate of 2 lbs or 2 pints per 100 square feet of planting bed. An alternative way to apply granular fertilizers starts with drilling or punching 6” deep holes at the drip line of the tree. Poured into these holes should be a total of 2 pounds of fertilizer per 1″ of trunk diameter (divided up and poured evenly between all of the holes). These holes should not be filled with more than 1/3 of the fertilizer and then they should be top filled with soil. This method of fertilization should only be done once a year, and is best done in late fall after leaf drop, or in early spring before bud break. Multi Purpose 10-10-10 Fertilizer works well.

Liquid fertilizers (such as Miracle Gro) are mixed with water and applied the same as you would water the plant (see product for specific details). This should be done three or four times per year starting in late April and ending in mid July. Stake type fertilizers can be used following the directions on the package. With any of the above techniques, a balanced mixture should be used; 20-20-20 or similar mix are good choices. Organic fertilizers, like manure, can also be used with good results. The material should be worked into open soil at a rate of one bushel per 6’ of plant or 100 square feet of bed area. As a plant matures, less fertilizing will be needed.

These evergreens need little winter care, but should be checked occasionally for rabbit, deer or other damage. If rabbit damage is found, you can protect the plant with a fence formed with hardware cloth (looks like chicken wire but with small square holes). To do this, the base of the plant should be tied up and a circle of hardware cloth can be placed around the outside. The base of the hardware cloth should be buried in the soil or mulch. This protection should be installed in late November and removed in mid April. Deer damage is challenging to control but, the repellents such as Repellex, Tree Guard or Liquid Fence Deer Repellent starting in fall and continuing through Winter can reduce problems.

The winter protection product “Wilt-pruf” should  only be used per manufactures requirements on this plant. Watering in late fall is very important for the winter health of any evergreen and should be done to young plants every year in early November. Even more mature plants can benefit from late season waterings, especially after a dry fall season.