Leyland cypress (Cupressocyparis Leylandii) is a fast growing evergreen conifer that can grow up to 4 feet a year, topping out at about 30 feet tall and 10 feet wide. If you don’t have your soil tested, adding fertilizer is likely not essential if the shoot increase is more than 2 inches a year. The best fertilizer for Leland cypress contains more nitrogen than phosphorus and potassium, the other major nutrients. How and when you apply it depends on the form of the fertilizer.
Climate, Soil and Nutrients
Successful development of Leyland cypresses requires more than adding fertilizer. They require sunny conditions though they can stand shade for part of the day. Their ability to take plant nutrients depends on the quality of soil, and they grow best in a soil with 5.5 to 6.5 soil pH. They could stand a vast range of soil as long as it drains well. They have shallow roots so weeds growing around a tree will compete for nutrients. Leyland cypresses will grow in U.S. Department of Agriculture plant hardiness zones 6 through 10.
Recommended Fertilizer
A soil test is the best way to discover a fertilizer for a Leyland cypress that’s right for your soil. Lacking a soil test, fertilize a adult Leyland cypress with 18-8-8 fertilizer. The three numbers show the ratio by weight of nitrogen, phosphorus and potassium. The sulfur is the important nutrient for trees. Fertilizers along with additional mineral ratios are acceptable, however, the sum of nitrogen ought to be equal to or higher than potassium and potassium. Start looking for a fertilizer that also contains what are known as minor or trace components. These might consist of secondary nutrients calcium, sulfur and potassium and also micro-nutrients iron, copper, boron, manganese and sulfur. You may apply the fertilizer in a slow-release type, sometimes called time-release fertilizer, or in water-soluble form.
The Way To Apply
While there aren’t any one-size-fits-all amounts of fertilizer to apply to your tree — the number depends on the brand and formula — there are a few general guidelines advocated by arborists. To determine the amount of fertilizer required for one tree, measure the trunk of the Leyland cypress 4 1/2 feet above the ground. If the trunk is less than 6 inches in diameter, apply around 2 2/5 oz of nitrogen. If the trunk is more than 6 inches in diameter, apply up to five ounces of nitrogen. Sprinkle the fertilizer on top of the ground to cover the main zone which typically extends as wide as the spread of the canopy, then water it well. To determine the amount of nitrogen in a bag, multiply the percentage of nitrogen in the bag by the weight of the bag. A 10-pound bag of 18-18-8 fertilizer includes 1 4/5 pound of nitrogen (.18 x 10). 1 pound equals 16 oz.
When to Employ
Applying an 8 to 9-month or a 12 into 14-month slow-release fertilizer in early spring will give your Leyland cypress each of the nutrients it requires for one year. It is also possible to employ a water-soluble fertilizer once or twice from spring to early fall. Don’t apply slow release fertilizers following July 15 because the plant might grow too quickly in late August and early September, not providing new development time to harden enough to adjust to winter cold. Applying pesticide during drought can injure roots by encouraging new development. Fertilizer will have its greatest effect three or three weeks after you apply it.