Selective Plant Shaping … An overview of Pruning and what it means to our gardens and varying plant groups

By Jan Boone

Image by Lewis Landscape Services, Inc.

Perhaps one of the most confusing things in our foothill’s garden work is also a key factor for our garden’s health and appearance, maybe even seasonal crop production.  When we look at the winter landscapes and think of the coming potential for our usual wet Spring snows and cold damage to pines, fruit trees or shrubs, we mustn’t forget that selective pruning may come in different ways throughout the cycles of our growing seasons.  Before you or I feel the urge to pull out hand saws, clippers or just our own nimble fingers, it’s beneficial to our plants and ourselves to review some plants and re-visit some basic techniques. Enhancing our know-how or simply modifying past favorite methods when it comes to shaping our plant landscapes can produce new and often valuable results.

Pruning really is a valued practice in our gardens.  The Valerian shrubs on my hillside and Nepeta (catnip family) plants along the driveway immediately come to mind.  Of course, the deer and elk often help w/the Valerian shaping but the Nepeta really has few worries, except for the occasional odd browsing by critters.  Alas, my cotoneaster is a frequent victim of browsing damage, so a good trim is usually called for after a hungry herd wanders through the yard! I have watched with amazement over the past few years a small white lilac that blooms along a dirt roadside near a house that has had infrequent work going on inside.  I’m amazed how it survives to bloom with only filtered light in pretty basic soils and absolutely no care pre or post bloom.  It must have resilient roots way down deep!  Many of our local houses enjoy spirea, viburnum or lilacs in their yards, especially as they produce their Spring branches filled with blossoms.  I’ve lost track of the times I get asked when is the best time to shape or prune these plants!  One of the best references I can share is CSUExtension Garden Notes #619 on Pruning Flowering Shrubs.  It includes shaping, shearing and thinning tips for these plant varieties.

Here’s a good list of reasons for pruning:  Help in allowing a plant to heal from weather related damage, also insect or general structural damage; to train plants or trees to enrich a habitat and/or to control size (i.e. clearing out plant suckers or squash runners); to prevent injury to people or from insects.  It is often helpful for the container and vegetable gardeners to prune, thus promoting flowering and fruit production.  Whether it is a diseased fir limb or an ignored fruit tree with erratic production; or even plants and vines in the vegetable garden, there will come the time you will want to consider pruning. 

Photo by Provident-Living-Today.com

When to prune may be the definitive question for every gardener.  Timing requires focused attention and expertise.  Sometimes by learning what doesn’t work on a favorite blooming plant or tree can reinforce what should have been done in a different manner or time frame!!  Don’t take the chance and instead refer to a good seasonal overview for pruning in Cornell University’s CooperativeExtension, Bulletin #23 An illustrated Guide to Pruning Trees and Woody Shrubs, page 27.  It provides a reasonable outline that you can monitor and adjust to your own garden and microclimate needs, also considering our altitude and quirky weather patterns.  For another good resource on pruning of fruit bearing trees.  Review CSU Fact Sheet#7.003 on Training and Pruning Fruit Trees.  There are also good CSU Fact Sheets on Aspens.   You should visit www.cmg.colostate.edu.  For Aspens, remember that dressing pruning cuts, cankers or wounds usually only provides safe harbors for the potential of insect and abiotic growth.

When thinking ahead to our upcoming spring & summer growing seasons for flowers and vegetables, knowing how to prune affords several options in productive methods These also apply to containers and ground plantings. Consider this … Do you recollect the differences in deadheading and pinching as opposed to utilizing a tool to cut??  Deadheading rids a plant of it’s spent flowers.  This has aesthetic appeal as well as the benefit of increasing blooms and potential fruiting. Many experts consider deadheading most effective in herbaceous annuals, encouraging renewed flowering for blossoms and may impact eventual fruit formation in differing varieties.  Deadheading also takes away dead tissue that can harbor insects or other abiotic diseases.  It also prevents a flower from setting seed.  Perennials that flower don’t rely on seed production, so the practice is not a good option.  Pinching is used to modify growing tips of herbaceous plants.   It’s often a go-to method in the vegetable garden to encourage additional fruit bearing branches. By removing the tips of branches, chemicals in the plant’s stem are activated to grow added shoots or branches, thus promoting a fuller appearance. 

Photo by Tractor Supply

For those striving for the elusive and ultimate heirloom tomato, pruning awareness is essential. In determinate tomato varieties, getting rid of suckers from the bottom of the main stem (which is reproductive) helps to open up the plant, making it fuller and more adaptive to additional growth. With indeterminate tomato varieties, prune up to the second flowering branch.  The stem is non-reproductive.  Finally, as you consider pruning, know the fundamental characteristics of your plant type.  Removing damaged or spent tree limbs is far different from encouraging tomato growth.  Do good research and be aware how microclimates and wildlife around your garden may impact the results of your efforts.

We cannot overlook the right tool for the right pruning job.  Pole and pruning saws are obviously of little help in your vegetable beds, but the correct hand clipper can save hours of frustration.  This is true when working on your ornamentals as well.  Last season’s Russian Sage flowering stalks will disappear quickly into the compost pile!  If you are using a pole, hand saw or other tool to work on a diseased tree or woody trunk of a large ornamental, disinfection of the tool afterwards is important.  Did you know that pruning cuts made at the peak of the growing season will normally carry a higher risk of transferring plant pathogens? Fire Blight is easily transmitted on dirty tools.   Research, clean and read labels carefully for your garden tool disinfecting.  Homemade remedies mixed with water can inadvertently do more damage than good.  Remember, manufacturers change ingredients, so check those labels.    Bleach solutions to disinfect may be preferable for many, but it will be corrosive on most metals. Research also shows the use of Isopropyl alcohol (70%) will not kill all bacteria.

A Good plant worth growing for enjoyment or food is also reliant on good soils, water and added supplements where warranted.  Take a look at potential candidates to prune now, as winter is here and branches are bare, then again as the seasons progress.  Your end result of selective plant shaping can optimize strength, form, aesthetics and crop output.  Enjoy the results of your thoughtful work this growing season!