Picea glauca 'Jean's Dilly' is a selection dwarf Alberta spruce, done so for its unique dark, green-gray foliage, narrow form and lack of propensity to revert. It is also extremely hardy, reported to survive down to USDA Zone 3a provided that it is totally covered for the winter. While it can take extreme cold it cannot withstand the drying sun and winds during the winter and early spring until the ground thaws.
After 10 years of growth, a mature specimen will measure 2.5 feet (75 cm) tall and 16 inches (40 cm) wide, an annual growth rate of 2 to 3 inches (5 - 75 cm).
This cultivar originated as a witch's broom found in the early 1980s at Iseli Nursery, Boring, Oregon; and named for the nursery's founder, Jean Iseli.
[Porterhowse Farms online catalog] Iseli nursery selected several dwarf mutations of dwarf Alberta spruce. This one, a dense conical shrub with short, thin needles is similar to the parent plant, but in a smaller scale. It was named in memory of Jean Iseli (Jean is pronounced as John).
[Iseli Nursery online catalog] An extraordinary dwarf form of the popular dwarf Alberta spruce. 'Jean's Dilly' (a reg. trademark of Iseli) grows at only one-half to two-thirds the rate of dwarf Alberta spruce, making it a perfect accent for small to moderate-sized landscapes. It is also an absolute gem for rock garden, container garden or perennial border. Perfect shape, slow growth, lovely texture and color, combine to create a remarkable little plant that will never outgrow its place in your garden. Grows 2-4" per year.