Pruning Tips for Winter and Beyond...

The Forest Hills Garden Club recently held a February pruning

program. Treasurer Nancy P. was the lucky winner to have

speaker Allen Gracey give her residential property a

professional pruning. Photo by the Forest Hills Garden Club.

By J.S. Corser

Durham Co. Master Gardener

 Most gardeners hope to give their clippers, trimmers and other gardening tools a four-month vacation during the winter, but some landscaping maintenance like pruning is important to do during February and the dormant months.

Pruning Guidelines
With general pruning, use the "three 'D's" as your criteria --"dead, diseased, and damaged." These types of branches should be removed whenever present on plants regardless of time of year.

The Science of Pruning
The terminal bud on a plant shoot produces a hormone (auxin) that inhibits the development of lateral buds along the shoot. When the terminal bud is removed, the lateral buds 6-8 inches near the pruning cut will become active and grow. Pruning cuts should always be made at a slight angle to promote water runoff and prune branches closely to the trunk for quickest wound healing.

Winter/Dormant Pruning
Timing is a key factor for successful pruning and growth training results. Horticulturists agree that late winter and early spring are the best times to prune most plants and cultivars. The key here is before bud break. This is true for summer flowering trees and shrubs and most evergreen shrubs. Examples of late winter pruning include: Abelia, Callicarpa, Buddleia,Chaste-tree, Crapemyrtle, Hibiscus, Roses, Hypericum, Ligustrum, Hollies, Nandina, Photinia, Waxmyrtle, Junipers (tip prune or light shaping only).

Other winter pruning factors:

• The foliage is gone and the structure of the branches is clearly visible.
• Winter pruning may lead to less contracted diseases like cankers and fire blights. 
• Some trees bleed large amounts of sap with winter pruning, trees such as: birch, honey locust, maple, dogwood, elm and walnut. They can be pruned during late spring, summer, or fall, but check the schedule of active parasites and diseases during these other seasons.
• In the case of oak trees, they should only be pruned during the winter when beetles are hibernating. (Freshly cut oaks emit an odor which attracts a beetle that causes oak wilt and eventual tree death.)

NC Extension Horticulture Specialist Dr. Mike Parker demonstrates cutting the central leader of two-year fruit trees. Trees are cut 28" from the ground to train and promote branch spreading for a large canopy. Wide canopies capture more sunlight for fruit production and more wind for pollination and disease control. Parker's pruning workshop was held Feb. 9, at the Central Crops Research Station, Clayton, NC.

Late Spring Pruning
Some varietals require late spring pruning immediately after their blooms fade. Some examples of these are: Azalea, Rhododendron, Barberry, Blueberry, Cotoneaster, Flowering Dogwood, Euonymus, Forsythia, Quince, Bush Honeysuckle, Winter Jasmine, Magnolia, Styrax, and Viburnum.

Summer Pruning
Fruiting and nutting trees and shrubs should be only be "trained" during winter, that is, the "central leaders" cut back to promote horizontal branching, but these types of trees should not be severely pruned in winter. (Winter pruning creates more vertical branch growth later, or "water spouts" which create excessive foliage and obscures sunlight necessary for fruit production. In addition, vertical branches are more vulnerable to breakage by heavy fruit crops, especially during NC hurricane season.) Summer pruning in June, on the other hand, removes the one-year, "redwood" growth leaving the tree structure a whorl shape optimal for crop production the next year.

For more information on pruning, click on these links to the NC Cooperative Extension:
http://www.ces.ncsu.edu/depts/hort/consumer/agpubs/ag-071.pdf
http://durham.ces.ncsu.edu/files/library/32/UNH%209.PDF