If you want to plant Leyland cypress trees, you have chosen a hardy and beautiful variety. Known for rapid growth, Cupressocyparis leylandii individuals often grow to between 50 and 80 feet tall. The tallest on record tops 130 feet. Many growers cite the hardy strength of these cypress trees as reason enough to withhold fertilizer. Others recommend fertilizer to increase the growth rate. Leyland cypress trees develop shallow roots and dislike intense heat.
According to AnythingGreen.com, Leyland cypress trees grow best in zones 6 to 10 and benefit from 14-7-7 fertilizer in slow or controlled-release forms. Lindstrom, Moorhead and Kent report in "Propagation and Care of Leyland Cypress as Christmas Trees" that the trees "respond well to periodic fertilization, especially in sandy soils. A 18-6-10+ minors fertilizer formulation has been used by many growers in Georgia. Slow-release formulations providing nutrient release over a 3 to 4 month period are preferred. For most applications, apply approximately 1 tablespoon fertilizer per foot of tree height in March and again in June to July. Place the fertilizer beneath the drip line of the tree crown."
Fertilizing Leyland Cypress in Eastern U.S.
According to a variety of regional gardening and horticulture guides published by Cool Springs Press in Tennessee, Leyland cypress trees grow well almost anywhere. In the Georgia guide-2003, authors report "Without fertilizer, Leyland cypress grows fast. With fertilizer, it grows even faster. Minimal fertilizer is best." In the Mid-Atlantic Gardener's Guide, Delaware, Maryland, Virginia and Washington, D.C.-2003, "Using a slow-release, organic, acid fertilizer, fertilize in fall and again in late winter/early spring."
In The Carolinas Gardener's Guide-2004, "Leylands prefer moist soil, so water diligently, especially in the first summer. Fertilize the second spring after planting, apply a slow-release fertilizer to increase the growth rate." As per New England Gardener's Guide-2003, "Using a slow-release organic fertilizer, fertilize in fall and again in early spring."
Fertilizing Leyland Cypress in Western U.S.
In the west, according to the Northwest Gardening Forum, growers recommend using 10-20-20 fertilizer with a caveat: "But be warned: if you give the trees a lot of fertilizer and water, they will grow at a brutal rate, and they will have a lot of space between branches. You may be able to make them denser with proper pruning."
According to OrganicGardening.com, Leyland cypress trees thrive using compost, manure and coffee grinds as an alternative to commercially prepared fertilizers.
A variety of gardeners recommend testing soil to determine whether or not your Leyland cypress trees need fertilizer. ArborDay.com reports that Leyland cypress trees tolerates many soils and grow well in full sun.