Even healthy Japanese barberry bushes, above, can benefit from a seasonal pruning late in the dormant stage, at right.

Old and overgrown Japanese barberry shrubs (Berberis thunbergii) lose their landscape attractiveness over time, crowding out nearby bushes, blocking sidewalks and obscuring home entries.

These dense, multi-stem shrubs have wiry branches that grow more than a foot annually. With this rapid growth rate, shearing the branches with hedge clippers does not keep the shrub's growth in check. To keep Japanese barberry shrubs healthy and well-shaped, conduct a rejuvenation pruning during the late dormant season.

Japanese barberry is a non-native, compact and dense deciduous woody ornamental that is deer resistant, making it an attractive option for home and commercial landscaping. Japanese barberry can become invasive outside of the home landscape and take over natural habitats.The bushes root by a process called layering, where branches that touch the ground create roots and develop new plants.Penn State Extension offers additional information about maintaining and controlling Japanese barberry shrubs outside of the home landscape at https://extension.psu.edu/japanese-barberry and https://extension.psu.edu/the-invasive-japanese-barberry.In the home landscape, prune Japanese barberry at the end of the growing season, after barberry shed their leaves. Bare branches allow full visualization of the plant's physical structure and make their prickly stems easier and safer to handle.While in this late dormant state, the stems can be cut back drastically to encourage new buds and growth. The cut wounds will be exposed to the weather for a short period of time before new growth seals them.

Conduct the rejuvenation pruning on a day with favorable weather. Gather all supplies, such as leather gloves, safety goggles and long-sleeved outwear. Pruning shears will work on the majority of stems and branches. A long handle lopper shears or pruning saws are best used to remove thicker branches.Position a tarp at the work area to collect the cut branches and debris, which lessens the amount of prickly materials to be removed from the site. Assess the shrub and decide upon the desired finished height and width. Remove all dead or damaged wood first. As a precaution for diseased wood, wipe tools after every cut with a disinfecting solution. Penn State Extension recommends a 1:9 solution, with 1/10 unscented, chlorine bleach to 9/10 water. Next, prune crossing branches, taking note of branches whose bark has been rubbed away or whose branches are indented. Remove any suckers and leaves that accumulated in the interior structure.

Once the dead and crossing branches are removed, reduce the number of interior stems by cutting them back to ground level. Prune the remaining stems 16 inches to 24 inches from ground level. Sunlight and air can now penetrate the bush from all sides. New buds and growth will appear as spring arrives. Barberry shrubs bloom on new wood. In the spring, yellow flowers will develop from the stem nodes, and the foliage color will vary with bright green, gold and burgundy leaves. Bright orange-red berries develop in autumn.Dispose of removed branches and clippings. Spread wood mulch around the base of the shrub in the spring if needed.Japanese barberry shrubs are fast growers that benefit from rejuvenation pruning to maintain their shape and health. If you have questions about Japanese barberry or pruning techniques, call the Master Gardener Garden Hotline at 724-287-4761, Ext. 7, or email the Master Gardeners at butlermg@psu.edu.<i>Lewis Palka is a Penn State Extension Butler County Master Gardener.</i>