White cedar, also called arborvitae, grows well in a variety of conditions. Its low cost, variety of forms and ease of care makes it a popular landscaping tree. Like most evergreen trees, white cedar requires little special care and fertilizer. While there are times when white cedar does benefit from fertilizer, sometimes you should avoid applying it to your tree. Making informed decisions about fertilizers helps ensure a long, healthy life for your white cedar.
Evergreen trees do not need fertilizer at planting time, and white cedar is no exception. You do not need to add fertilizer to the planting hole when planting your tree, but if you do, the University of Wisconsin Extension recommends using only slow-release fertilizers in packet or pill form.
White cedar usually does not require fertilizer, according to Ron Smith, a horticulturalist with the North Dakota State University Extension. If you use fertilizer, he recommends applying Miracle-Gro annually, in the spring. The Ohio State University Extension offers a similar recommendation, prescribing lawn fertilizer for white cedar. However, they caution to avoid any that contain weed killers, which might damage your tree. If you prefer an organic solution, mulch around the tree with well-rotted manure or work it into the soil, advises the University of Wisconsin Extension.
By providing for the nutritional needs of your tree, fertilizer ultimately promotes new growth. Avoid fertilizers when you don't want your tree to produce new growth.
Although cedars generally thrive without extra help from fertilizers, you should also know the signs that your trees might be nutrient-deficient, allowing you to judge when fertilizer might be warranted. Poor growth, small leaves and yellow foliage indicate a possible deficiency in white cedar. However, other diseases and pest problems present similar symptoms. A soil test can correctly determine soil fertility needs and help you choose the best fertilizer for your tree.
Its extreme cold hardiness makes the white cedar an appealing choice for homeowners in areas that experience harsh winters. However, according to Smith, winter desiccation is the most common problem white cedars experience, and fertilization can exacerbate it. Late-season fertilization causes new growth that becomes susceptible to damage in the cold and causes the tree to lose water.