Leyland Cypress Sunlight Requirement

Leyland Cypress and Thuja Green Giant trees will tolerate partial shade. We want to discuss the canopy situation, shade on one side, even how being in the North or South can effect a shady planting site.  We also will cover the symptoms of too much shade, providing light by pruning the offending shade trees and also a good substitute for shady locations.

A straight overhead canopy of shade is not the preferred situation for Leyland Cypress and Thuja Green Giant trees. The absolute worse situation is an overhead pine or evergreen canopy, because the trees under an evergreen canopy don’t even get light during winter. If that is your application, don’t plant there. Sometimes it cannot be avoided. For example, in Long Island and in the Hamptons area, some neighborhood have rules about what can be cut and are very strict about cutting native trees to replace with anything not native to the area. Even so, I am not recommending planting Leyland Cypress or Thuja Green Giant trees under a canopy.  I have planted these varieties under a canopy that was very high and still it effects the trees.

Northern locations tolerate shade trees better than southern locations! If the trees bring the shade are deciduous tress, at least after those canopy trees shed their leaves, the Leyland Cypress trees will get full sun all winter. This is more beneficial from NY and northward than in southern states, because they shed one month earlier in fall than in the south and don’t green up till one month later than southern deciduous trees. On Long Island, Thuja Green Giant or Leyland Cypress trees planted under a partial canopy of scrub oaks may get full sun for seven months of winter before leaves re-appear, whereas southern states with a similar situation may only provide five months of full sun. Shade on one side of your row is normally fine, because your Leyland Cypress trees will still get the powerful straight overhead sunlight. Thuja Green Giant or Leyland Cypress trees can grow three feet per year if fertilized properly, so remember if there are slower growing trees shading on one side, The Thuja Green Giants or Leyland Cypress will out-grow the shading trees in most cases and will have more sun after that time.

The main symptom of too much shade on Leyland Cypress and Thuja Green Gants is the trees thin out. When you first plant them if Ball and Burlap field grown trees, they will be thick at first. Over the years, shady applications will take their toll and they will thin out somewhat.  Slow growth is the second symptom. As I stated above, shade to one side will not cause thinning, lack of straight overhead sunlight is the problem.

Providing light by pruning the offending shade trees is a great idea! If you cut limbs off an evergreen tree that is shading your Leyland Cypress row, those limbs will not grow back so it should be a one-time effort. If you have arborists trim deciduous trees like Oaks, Maples, etc it is more likely to require trimming again at a later date. If the trimming on deciduous trees are cut all the back to the trunk, on the side that shades your Thuja Green Giants you may solve it completely. The advice here is do the tree surgery above before you plant the privacy screen row below. The arborist will probably be able to let the limbs fall if it is done before planting the Leyland Cypress row, while if you wait till after planting, the arborist will likely have to rope the limbs down to prevent damage on your privacy screen below.

Consider substituting Nellie Stevens Hollies for shady applications. Also remember, if you are planting in an established wooded area, the trees nearby not only rob sunlight but will have established root systems that will compete with your new plants for  moisture.