Japanese Holly (Ilex crenata)
Japanese Holly is among the most valuable of all the Holly species. Japanese Holly has a distinctive, dense branching growth habit and fine-textured evergreen foliage. It actually resembles boxwood more than traditional Holly. Slow growers, Japanese Holly shrubs may live to over 80 years of age. There are hedges in Japan that have been maintained for so long and have become so dense that they can be walked upon and you would not fall through.
Japanese Hollies grow from 3 to 15 feet tall, depending on the variety. A typical shrub will spread 2 to 10 feet and have a dense rounded habit.
Japanese Holly leaves are small and broadly oval, 1/2 to 1 inch long, up to 1/2 inch wide. They have fine-toothed edges rather than the distinctive-spined leaves of most Hollies. They are a glossy dark green above, lighter beneath. Leaves of some varieties are slightly cupped.
Japanese Holly flowers are so tiny that they are virtually insignificant. They are creamy-white and have 4 tiny petals. Male flowers grow in small clusters where leaves join stems. Female flowers are solitary or in smaller clusters on separate shrubs. Flowers of both sexes appear in late spring or early summer. They are favorites of bees that aid pollination. Inconspicuous black berries, about 1/4 inch in diameter, develop in mid-autumn and last into early spring. Some varieties have yellow berries.
Japanese Hollies can withstand very severe pruning which is why it make such wonderful hedges. The key is to not prune new growth until it hardens off, which is when the tender green stems begin to turn woody.
Japanese Holly Choices
The many cultivars of Japanese Holly give you choices in size and in some case color of leaves. The varieties Convexa and Microphylla have been most widely grown for years and are still among the best, though some 40 other varieties are currently being grown. Convexa: Leaves cupped, deep green, shiny. Height 3 to 5 feet, spread 4 to 6 ft. Compacta: Similar to Convexa, but more compact, better foliage color. Grows 4 to 6 feet high and is ideal for a hedge. Dwarf Pagoda: very dwarf, compact , upright. Glory: (male) compact, globe form; an excellent pollinator. Helleri: dwarf form, very compact growth. Height to 3 feet, spread to 4 feet. Kingsville: height to 4 feet, spread to 7 feet. Hardy north to Zone 5. Midas Touch (male) has variegated foliage with blotches of yellow on the green leaves. Snowflake has white edges on leaves.