Juniperus procumbens, as described in 1870 by (Siebold ex Endlicher) Friedrich Anton Wilhelm Miquel (1811–1871), in Flora Japonica, 2nd edition, is commonly known as Japanese garden juniper; as well as 地柏 (pu di bai), sonare, or hai-byakushin in the Japanese language. Its status as a wild plant is disputed; some authorities treat it as endemic on high mountains on Kyūshū and a few other islands off southern Japan, while others consider it native to the coasts of southern Japan (north to Chiba Prefecture) and also the southern and western coasts of Korea. It is closely related to Chinese juniper (Juniperus chinensis), and is sometimes treated as a variety of it, i.e.Juniperus chinensis var. procumbens.
Description. Japanese garden juniper s a prostrate plant, which usually grows between 8 to 12 inches (20 – 30 cm) tall, although sometimes as high as 20 inches (50 cm). While it does not get very tall it can get quite wide, 12 to 16 feet (2 – 4 m) across or more, with long prostrate branches.
The branches tend to intertwine and form a dense mat.
The leaves are arranged in decussate whorls of three. The leaves are mostly of juvenile form, growing needle-like, individually measuring 0.24 to 0.32 inch (6 – 8 mm) long and 0.04 to 0.06 inch (1 - 1.5 mm) broad, with two white stomatal bands on the inner face. Occasionally one will find adult (scaled foliage), particularly on potted specimens.
Plants are dioecious with separate male and female plants.
The pollen cones measure 0.12 to 0.16 inch (3 – 4 mm) long, and shed their pollen in early spring.
The seed cones are berry-like and globose, measuring 0.32 to 0.36 inch (8 – 9 mm) in diameter, colored dark blackish-brown with a pale, blue-white waxy bloom, and contain 2 or 3 seeds (rarely 1). Seeds mature about 18 months after pollination.
Distribution. This species is native to Japan — Kyūshū and Bonin Islands. Hardy to USDA Zone 4 (cold hardiness limit between -20° to -30° F / -28.9° to -34.4° C
Cultivation and Uses. Several cultivars have been selected for cultivation, the most widely grown being 'Nana', a slow-growing procumbent plant. Others include 'Bonin Isles', a strong-growing mat-forming plant collected on the Bonin Islands, and 'Green Mound', which may just be a renaming of 'Nana'. A variegated plant sold under the name Juniperus procumbens 'Variegata' is actually a misnamed cultivar of Juniperus chinensis.
Juniperus procumbens — a closeup of juvenile and adult foliage, as well as a few pollen cones.
Photo by Reid Parham
Juniperus procumbens — a closeup of juvenile and adult foliage.
Photo by Reid Parham
Y’all have this plant listed as only producing juvenile needle foliage, but I have seen many instances where this species produces mature scale foliage. Are you willing to update the description? It is true that procumbens is usually all juvenile needles, but when grown in pot culture they are widely known to produce mature foliage.