Picea orientalis 'Firefly' / Firefly Caucasian spruce
Picea orientalis 'Firefly' is a dwarf conical selection of Caucasian spruce with dense, symmetrical branching and stunning golden foliage that is dark green in the shaded parts of the plant. This conifer can be a conundrum with respect to initial siting in the garden. If planted in too much shade, 'Firefly' will be mostly green. When exposed to hot afternoon sun before setting deep roots, the golden foliage will burn, particularly on the upper branch surfaces. After several years in the landscape, it will become more tolerant of full sun. We recommend patience.
After 10 years of growth, a mature specimen will measure 6 feet (2 m) tall and 4 feet (1.2 m) wide, an annual growth rate of 3 to 6 inches (7.5 - 15 cm), about half the rate of 'Skylands.' Be aware that the original plant in the Jean Iseli Memorial Garden in Oregon grew very slowly until very recently and has started to "speed up" in its growth rate. Also, given that these plants are propagated through grafting, propagants will gain a bit of extra vigor from the understock.
This cultivar originated as a seedling selected in the 1990s at Iseli Nursery, inc. Boring, Oregon, USA. For years, it carried the provisional name of [Skylands sdlg #1] and may been seen growing in arboretums and nurseries with this name. Iseli Nursery details more of this exciting new plant's history at this link.
'Firefly' grows about 6 inches per year for many decades if not centuries. No tree will grow to a specific height and stop unless it's dead. It's fully hardy in USDA Zone 6a. See the link for specific climate data from this species' origin. Match it with your own to figure out if you plants will thrive or survive.