Plant taxonomy classifies privet shrubs under the genus, Ligustrum. Indeed, they are commonly referred to as "ligustrum shrubs," too. Within that genus, there are various species and cultivars, some of which I will mention below.
Privet bushes are so commonly used in hedges that they are often referred to as "privet hedges," as if how they are used in landscaping trumped their identity as a particular kind of shrub.
Plant Traits, Some Varieties, and Their Growing Zones
Common privet shrubs (Ligustrum vulgare) reach a height of 4-15 feet with a spread of 4-8 feet. These fast-growing shrubs bear white flowers in late spring-early summer; blackberries succeed the flowers. Knowing that this plant bears blackberries is useful for identification purposes since this is not an especially common color for a shrub's berry to have (although some types of holly shrubs share this characteristic with Ligustrum).
But these shrubs are grown primarily for the dense foliage they can provide when pruned into hedges. That dense foliage -- along with their height -- means that they afford good privacy during the summertime when folks are most active in their backyards. Here is a list of some of the various kinds of privet (note that the zone information provided refers only to hardiness; a shrub may be cold-hardy to zone 5, but that does not imply that it is evergreen there):
- Common privet (L. vulgare): zones 5-8.
- California privet (L. ovalifolium): zones 5-8
- Golden privet (L. ovalifolium 'Aureum'): zones 5-8
- Golden Vicary (L. x vicaryi): zones 5-7
- Border privet (L. obtusifolium): zones 3-7
- Amur privet (L. amurense): zones 3-6.
- Japanese or "wax" privet (L. japonicum): zones 7-10.
- Chinese privet (L. sinense): zones 7-9.
Another kind commonly referred to as a "Chinese" privet is L. lucidum (USDA zones 8-10), which can grow to be a small tree, reaching a mature height of 20 feet tall.
Michael Dirr critiques these and other types of Ligustrum with his usual swagger in Dirr's Encyclopedia of Trees and Shrubs (Pages 442-449). He calls L. japonicum and L. obtusifolium "respectable," while he seems to have the most disdain for L. sinense, which he describes as "a terrible and devastating escapee that terrorizes floodplains, fencerows, and even open fields...."
Golden and/or variegated leaves are among the best-looking. The leaves of L. ovalifolium 'Aureum' have green centers with golden margins, while Vicary is a solid gold. Dirr also lists some types where the variegated leaves are marked by "gray-green mottling" and "cream-silver edges"; namely, three cultivars of L. japonicum:
- 'Jack Frost'
- 'Silver Star'
Plant Care Tips: Pruning, Sun and Soil Requirements
- Shear these bushes after they have flowered; thereafter, shear them an additional three or four times during the course of the summer. Privet hedges will fill in better (that is, the plants will become bushier) if they are pruned frequently. You can read tips here for how to trim hedges.
- Privet hedges can be grown in partial shade to full sun.
- Grow these shrubs in a soil that is kept evenly moist. They tolerate a wide soil pH range.
Uses for Privet Shrubs in Landscape Design, Warnings
The privet shrubs cold-hardy enough to be grown in the North are used almost exclusively to form hedges or topiaries. Many kinds are not especially beautiful plants when considered in isolation, but they do excel in the role of hedges (although it can be argued that there are far better choices out there). They grow more quickly and can be shaped more easily than can boxwood shrubs, for instance (another shrub widely used in hedges). Privet hedges tolerate heavy pruning. They do not seem to be troubled by the pollution that plagues many other plants in urban settings, plus they are salt-tolerant plants (that includes standing up well to road salt). These last two points are important considerations if you are seeking plants for a hedge that will run along a street. In fact, privet's popularity, traditionally, can be attributed, in part, to its carefree attitude about what kind of soil you grow it in (yew bushes, another old-time favorite, display a similar lack of fussiness).
Despite the strong arguments just made in favor of privet hedges, the plants do not come without drawbacks. First of all, they are poisonous plants. Secondly, not being evergreen in the North, privet hedges will be attractive for only a portion of the year there; for the same reason, they cannot furnish privacy year-round. Finally, privet shrubs, which are indigenous to the Old World, are invasive plants in North America; many choose not to grow them for this reason, alone.
As someone who landscapes in frosty New England (USA), I prefer shrubs that are truly evergreen here for hedges, such as Canadian hemlock and arborvitae. Read my full article to learn how to plant hedges.