Taxonomy and Botany of Japanese Barberry Shrubs
Plant taxonomy classifies Japanese barberry shrubs as Berberis thunbergii. Cultivars include 'Crimson Pygmy' and 'Aurea.' Another well-known species is the common barberry or "European" barberry (Berberis vulgaris). A type with variegated leaves is Berberis thunbergii var. atropurpurea 'Rose Glow.'
Shrub Characteristics, Warning, and Origins of the Names
Japanese barberry shrubs often reach a height of 6 feet at maturity, with a similar spread. More compact cultivars ('Nana' and 'Compactum') do exist.
The bush bears green leaves, as well as yellow flowers that bloom in mid-spring. It also has sharp thorns, and red, oblong berries that last well into the cold-weather months. The latter trait is valued for the winter interest that it gives.
This bush is considered more of a foliage plant than a flowering shrub, although it does produce blossoms. Even then, it is only some cultivars that are worth mentioning as foliage plants (except for in the fall season). These would be the cultivars that bear leaves of a color other than green (red, golden, etc.).
In autumn, even the leaves of the species plant can develop some nice color (often reddish or orange). Whereas both B. thunbergii and B. vulgaris lose their leaves in winter, B. julianae is an evergreen type (6-8 feet tall by 4-6 feet wide, hardy to zone 6).
Attention: Both Japanese barberry and common barberry are invasive plants in North America. This article is offered for research purposes only. Its publication in no way represents an endorsement of the planting of barberry. These bushes can spread both by seed and from their root system. In fact, new roots may develop even where a branch makes contact with the soil. For more on the invasive aspect of the bush, see the "Invasive Plant" section below.
"Barberry" and its genus name, Berberis derive from the Arabic name for the fruit, barbaris. Both the plants themselves and the berries they produce can be referred to as "barberries." The species name, thunbergii comes from the name of botanist, Carl Peter Thunberg (1743-1828), a great plant collector who brought Oriental plants back home to the West.
Planting Zones, Sun and Soil Requirements
Other than requiring a well-drained soil, these shrubs tolerate a wide variety of growing conditions. This tolerance helps account for the shrubs':
Specifically, they tolerate pollution well. They are also shade-tolerant shrubs and drought-tolerant shrubs. In spite of their tolerance for shade, they will give a better display if grown in an area with full sunshine.
Uses for Common and Japanese Barberry Shrubs in Landscaping
Traditionally, these shrubs were used in hedges. With their sharp thorns, a row of such plants would, in fact, serve nicely as a "living fence." To get a hedge to fill in quickly, space the plants about 3 feet apart when you first put them in the ground.
The bushes are also effective for erosion control. One of the most deer resistant shrubs known, they are especially popular in neighborhoods overrun by deer. Indeed, they have few pest or disease problems.
As mentioned above, 'Crimson Pygmy,' 'Rose Glow,' and 'Aurea' are three Japanese barberry cultivars. 'Crimson Pygmy', true to its name on both counts, bears reddish purple foliage and stays short (at most, half the height of the species plant, and usually less, so approximately 2-3 feet tall). 'Aurea' is also something of a dwarf (3-4 feet tall). Its foliage starts out a vibrant yellow. 'Rose Glow' attains the same mature height (6 feet) as the species plant. Its claim to fame is the fact that its leaves have three colors. Its leaves sport red and purple colors, streaked with off-white.
But Berberis thunbergii is an invasive shrub in North America, where the bush has naturalized in some areas. For example, it can be seen all over the woods in the Quabbin Reservoir in Massachusetts, where barberry shrubs had been grown as landscape plants when people lived on the land. They have since multiplied, and they have spread beyond belief.
It also seems that growing the cultivars, instead of the species plant, does not solve the problem. According to Boston.com, Jonathan Lehrer, at an invasive plants conference, "presented a study that found Japanese barberry cultivars such as the popular Crimson Pygmy can...produce seedlings that revert to the more invasive green form."
But soon you will be able to buy a Japanese barberry shrub that is not invasive. Researchers at UConn have developed sterile cultivars of Japanese barberry that began hitting the market in the spring of 2018. These noninvasive barberry shrubs may take a while to reach your local garden center. But there should be no rush, especially if you are not a big fan of prickly plants. Landscaping with barbed wire is not everybody's idea of fun. An invasive plant that is much more tempting to grow, in the opinion of many gardeners, is burning bush shrub.