Pruning

Here in Utah we are in the dead of winter. However, there is still yard work to be done. Besides cleaning up the dead leaves and plants that you never got around to last fall, now is a great time to prune your non spring-flowering shrubs and all your trees.

Why prune in winter?

During the winter most plants loose their leaves and go into dormancy. As they lose their leaves, they suck all the carbohydrates and other good stuff out of the leaves and into the trunk and roots. That means that when you cut a branch off in winter, the tree won't go into shock because it's energy isn't really stored in the branches or leaves like it is in the summer.

In addition, there are less bugs around during the winter to infect the open wound you make when you cut a branch off.

Why not prune spring flowering shrubs now?

Spring flowering shrubs form their flower buds in the fall and early winter. That means if you prune off a branch right now, you won't have as many flowers in the spring. Spring flowering shrubs can be pruned after they flower. Summer flowering shrubs form their buds in the spring so it is okay to prune them now. Non flowering shrubs can also be pruned now.

Examples of spring flowering shrubs: Lilac, Forsythia, Viburnum, Magnolia, Bridal Wreath Spirea, Azalea, Dogwood, Weigela and Quince.

Examples of summer flowering shrubs: Rose of Sharon, Japanese Spirea, Rose, PeeGee Hydrangea, Butterfly bush, Smoke Bush, Potentilla, Blue Mist Spirea

Why prune?

There are a number of reasons you may need to prune.

• Create a strong structure so that branches won't break off later. This is especially important with large trees.
• Open the plant up so it can get more light or air circulation. Roses and fruit trees need this.
• Reduce the size of the plant.
• Remove dead or diseased branches.
  
• Make the plant more dense. This is done by shearing or heading cuts. When the top of a plant is cut off, the apical meristem (the growing point on a plant) is removed and this causes a change in hormones in the plant, which usually promotes growth from lateral buds. Usually the plant will sprout from two buds, which makes the plant bushier. Please do not do this to a tree! Topping a tree is bad for it!

Proper Pruning Cuts

There is a lot to know about pruning and I am not going to write it all right now, but the most important thing to know is you should never cut a branch flush with the truck of a tree or shrub. This destroys important tissues and prevents the pruning wound from sealing over. The diagram below shows a proper pruning cut. Note how the cut is not made parallel to the trunk.


Different pruning for different plants

Some plants require special pruning techniques. almost any kind of tree or shrub that produces fruit will need to be pruned a specific way. I would recommend checking out a book from the library that tells how to prune your specific type of fruit-bearing plant.

Mophead hydrangeas also need special pruning because most varieties only bloom on old wood.

Roses also need to be pruned a specific way.