Ask Mr. Smarty Plants

This tree has a very interesting story. It is a hybrid, which means it does not appear in our Native Plant Database, of two trees that are native to the North American Pacific Coast, Cupressus macrocarpa (Monterey cypress) and Cupressus nootkatensis (Alaska cedar). It hybridized naturally because the two trees were taken to an estate in England and were close enough together to cross pollinate. Ordinarily, in their native habitats in the Pacific nothwest, they would have been 400 miles apart and would never have hybridized. Then, later, the resulting hybrid, Leyland Cypress, was exported back to the United States.

Here is an excellent article on Leyland Cypress. It's kind of small print, but we think it will be helpful to you. Many people look for a tree with a taproot, like a carrot has. They think that it will grow straight down and the roots won't get into their lawns or swimming pools. But if you consider, you can see how a root like that could cause the very problem you have. Taproot trees develop outlying roots to get more water and nutrition from the soil, but also to stabilize the tree in an upright position. It looks like your tree didn't quite get stabilized.

One note we saw on caring for this tree is that you should avoid growing in moist unstable soils - in windy areas the trees may blow over due to their rapid growth rate. Leyland cypress is a large tree unless constantly trimmed, do not plant too close to structures. That might have something to do with your tree leaning, the kind of soil it is in.

We want to point out that the parent plants of this tree are both native to areas completely across the United States from Maryland, so we are not sure how well acclimated your tree is to your soils and climate. Since we have no personal experience with either the tree or with tree staking, here is an excellent article on the procedure from Colorado State University Extension Tree Staking and Underground Stabilization.