To plant a Leyland cypress tree, wait until the tree is dormant, and plant it in a hole approximately three times wider than the root ball. Dig the hole deep enough to cover the root ball up to the flare at the bottom of the tree trunk. Choose a location with well-draining soil and full sun or partial shade. Apply mulch to the base of the tree, and tie the tree to a stake.
Cover the root ball with dirt, allowing 2 inches under the tree collar to remain uncovered. Install a drip irrigation system to promote healthy growth in dry weather, or deeply water the roots twice each week. Water mature trees less frequently, and avoid overwatering.
Tie the tree to the stake loosely using a rubber strap or several twist ties. Loosen the strap or ties as needed to prevent the device from growing into the tree.
Remove the stake after six months to one year, or when the tree is strong enough to withstand wind and rain. When applying mulch, place the mulch approximately 6 inches away from the tree trunk. Space the trees 10 to 12 feet apart to form a hedge, or space them 4 to 6 feet apart when growing holiday trees.