When Is a Good Time to Prune Nellie Stevens Hollies?

Characteristics

• "Nellie R. Stevens" holly is a hybrid plant, developed by crossing English holly (Ilex aquifolium) and Chinese holly (Ilex cornuta). It is an especially vigorous plant that grows quickly, taking on a broadly pyramidal shape and reaching a height of up 20 to feet and a width of 10 to 12 feet when mature. It has exceptionally dark green leaves that have sharp points typical of holly leaves. Male and female flowers are borne on separate plants and a female needs a male plant nearby, either of this variety or a Chinese holly, to produce an full crop of red berries, although it can develop a few berries without pollination.

Timing

• Pruning a "Nellie R. Stevens" holly bush in late winter helps ensure an abundance of berries the next year, because it gives the plant an entire season to grow new stems that bloom and produce fruit. You can also cut the plant back as the holiday season approaches, to have fresh holly sprigs for decoration, without interfering with the next season's berries. Although "Nellie R. Stevens" holly is a tough plant that handles cold well, it's best not to prune it in late summer or early fall, because this stimulates tender new growth that might be harmed by an especially cold winter.

Pruning

• "Nellie R. Stevens" holly requires no extensive pruning, but you can train a young plant into a more treelike shape by removing all but one or two main stems, which will become its main trunks, and cutting back any new central stems or side branches that form near its base. You can also prune to help control the size and shape of a shrubby plant, cutting back some branches by about one-third every year or two. It's best to trim individual branches rather than shearing the entire plant, since shearing tends to promote heavy surface growth that can exclude sun from the plant's center and can also lead to an unattractive, clipped appearance with damaged surface leaves.

Techniques

• When removing a large branch from a "Nellie R. Stevens" holly, use a heavy pair of pruning shears or a saw, depending on the size of the branch. If the branch is large enough to have a collar, or slightly thickened zone at its origin, make the cut flush with the collar so that this thickened base remains on the plant. For smaller branches and twigs, choose a vigorous bud that points in the direction in which you want new growth to appear and cut just above the bud, leaving a tiny stub and ensuring you don't injure the bud.