Pinus thunbergii 'Thunderhead' is an attractive, vigorous, broadly pyramidal selection of Japanese black pine with densely packed, long, brooding, dark-green needles and distinctive silver-white candles that are most attractive in late winter/early spring. After 10 years of growth, a mature specimen will measure 12 to 15 feet (4 - 5 m) tall and 20 feet (6 m) wide, an annual growth rate of 12 to 15 inches (30 - 37 cm). Like all cultivars in this species, specimens can be easily aesthetically pruned to control a plant's size and form.
As is true with most Pinus thunbergii, 'Thunderhead' is hardy to USDA Zone 5 although the needles could burn at temperatures of -10 to -15ºF (-23 to -26ºC). Plants are especially vulnerable during times of wide and rapid temperature fluctuation. If possible, winter protection from the effects of wind chill could greatly increase your odds of successfully maintaining this plant in your garden.
This cultivar originated as a seedling selected around 1987 by Angelica Nurseries, Massachusetts, USA. It was originally released under the provisional name, [Angelica's Thunderhead] and at some point the cultivar name became shortened into its present form.
One must note that in 1981, Dr. Sidney Waxman of University of Connecticut selected and named a Pinus resinosa under the name 'Thunderhead.' Under the rules of botanical nomenclature, a cultivar name can only be used once within a genus, leaving P. thunbergii 'Thunderhead' as an illegitimate cultivar name because P. resinosa 'Thunderhead' was named first. I would be most appropriate if 'Angelica's Thunderhead' was re-adopted as a cultivar name for this conifer.
