Cryptomeria japonica 'Tenzan' is a very small and extremely dense flat-topped cushion, wider than tall, with short, prickly, robust and tight dark-green foliage that turns bronze-red in winter. 'Tenzan' is less hardy than other cultivars of Cryptomeria and is prone to burning in the hot sun. Typical rate of growth in most areas is less than 1/2 inch (1 cm) a year, resulting in a tiny bun, 6 inches (10 cm) wide and somewhat shorter after 10 years in the garden.
This is one of the smallest known cultivars of the species. It originated as a witch's broom found in the mid-1970s at the Nelis Kools nursery in Duerne, The Netherlands. It is a perfect selection for a sheltered rockery or trough garden.
The RHS database lists this cultivar as 'Tenzan-sugi' which is incorrect. The use of "sugi" with Cryptomeria cultivars is considered redundant, as "sugi" means "cedar" in the Japanese language.