Answer: Leyland cypresses can grow 3-4 feet a year and reach an ultimate height of 30-40 feet with a 12-15 foot spread. While you can prune yours each year, I don't think you will be able to keep it only 10 feet tall and 4 feet wide. Instead, why not grow a Dwarf Alberta spruce (Picea glauca 'Conica') which remains under 10' at maturity, or a Hick's Yew. These won't require severe pruning the way a Leyland Cypress will and they will provide that evergreen look to your landscape.
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