Cupressus×leylandii'Castlewellan' is a very strong-growing, broadly upright selection of Leyland cypress with greenish yellow young shoots of foliage that darken to more a typical green over course of the season. After 10 years of growth, a mature specimen will measure 16 feet (5 m) tall and 6 feet (2 m) wide, an annual growth rate of 18 to 24 inches inches (45 cm - 60 cm).
This cultivar originated as a seedling selected in the early 1960s by John Keown of Castlewellan, Northern Ireland, United Kingdom. Notable is the fact that in this case, one of the parents involved in the hybridization was Cupressus macrocarpa 'Lutea.' The plant is often seen mislabeled under the name, 'Castlewellan Gold.' In addition, 'Barden's Gold' and 'Galway Gold' are also common misnomers.
Cupressus × leylandii 'Castlewellan' — a mature plant in a private garden in Czech Republic.
Photo by Milan Havlis
Cupressus × leylandii 'Castlewellan' — a closeup of foliage detail.