|
Garden Notes: Pruning—Why, When, and Who |
| Print |
|
E-mail
|
|
Written by Story and photos by Dianne Stortz-Lintz
|
|
Wednesday, 01 October 2008 |
Pruning is one of those gardening chores that do not have to occur. That’s right, I said it: Pruning is not necessary. Pruning is, however, important if you want a well-shaped and thrifty plant. The main point of pruning is to improve the plant in some way that benefits humans.
A plant will survive without any pruning. It might be ugly, but it will probably live. Many plants are pruned for the wrong reasons, at the wrong time, and by people who don’t know or care what they are doing. To get the best effect from pruning, it is important to know why you’re pruning, when to prune, and when to call in the professionals.
Pruning re-directs growth, stimulates new branches, increases air flow and light penetration, increases flower and fruit production, removes dead and dying tissue, improves structure, reduces hazards, and increases the life of the tree or shrub. So if you feel the need to prune, I’m going to elaborate on the reasons why we prune. There are a myriad of reasons why one should prune shrubs and trees.
Safety
It is wise not to ignore pruning for safety. All of these issues should be addressed to prevent damage to your home, neighbors, family friends, and pets, prevent liability, and save money in the long run.
• Damage done by falling trees is often substantial and the cost of removing a fallen tree is significant. Proper pruning of trees can reduce tree and branch drop by encouraging a strong branching structure.
• Shrubbery or low-growing tree branches that block visibility of a roadway or intersection need to be pruned to prevent sight barriers.
• Branches that are interfering with power or phone lines or growing into buildings need to be removed.
• Storms can break branches but leave them hanging like the sword of Damocles; a large branch dangling from its bark is a serious liability and should be removed.
Disease Control or Prevention
Pruning can remove damaged or diseased branches which in turn decreases the chance that an infection can occur or spread. If you don’t prune diseased branches, you are significantly increasing the chance that your plant will die.
Increase Light and Air Into the Base
This is a vital concept for many flowering shrubs, in particular, roses. Because roses produce the best and strongest canes from the base, it is vital to get light to those new canes so that they can grow big and strong.
When a plant has too many branches, it will often decrease the amount of air that can move through the canopy. Moist stagnant air around the canopy increases the incidence of disease. This is more of an issue with shrubs than trees, but trees are not immune to this problem.
Rejuvenate Plants
Often pruning older shrubs and trees directs the energy into new growth that restores the vital look to the plant. There are limitations to this practice. Although there are some shrubs that tolerate being totally mowed to the ground and may benefit from it, in general, rejuvenation should be performed in a stepwise fashion and done over a few seasons.
Increase or Decrease Flowering and/or Fruiting
This is yet another valid reason to prune. Depending on the species of plant, you can increase or decrease the production of fruit and flowers by pruning.
There is a whole science to properly pruning fruit trees for maximum yield. While pruning fruit trees properly increases fruiting, the converse is also true. Therefore, if you don’t want fruit from your apple tree, prune it like a shade tree. You’ll still get some fruit but not as much.
Improve or Modify Form of the Plant
In my opinion, this is where we’re getting into the shady, often not-so-optimal reason to prune.
Pruning fruit trees into an espalier to grow along a fence or shaping a Hollywood juniper to look wind blown is a nice way to add variety to your landscape. Formal hedges using plants that lend themselves to hedging help section off your yard.
Carving a flowering shrub like viburnum into a tidy angular box is just wrong. If you want to take a nice flowering shrub and make it into green box, save your time, money, and resources and build a wooden box and paint it green. Viburnums are large and vibrant bushes with great flowers, a wonderful arching habit, good berries for birds, and wonderful fall foliage. When you hedge viburnum, you get no flowers or berries and they develop rank ugly growth.
Even though I’m not fond of it, pruning and training plants into topiaries remains very popular. Topiary is the art of pruning and training a tree, shrub or other plant into a recognizable shape. These come in many forms including bears, dolphins, race cars, squirrels, and the like and are very labor-intensive.
Make a Plant Fit Into a Space
In my opinion, the highest and best use of this reason to prune is to prune a fruit tree to so that it remains short and easy to harvest. Yet another example is the judicious pruning of any plant to keep its original shape and to keep it small and fit into a small space. This type of pruning usually requires a good eye, experience and time to pull off correctly. Bonsai is an art form that utilizes this technique and, like topiaries, Bonsai requires a lot of work.
The darker side of making a plant fit is the type of pruning used to rectify the “Too-many-plants-too-close-together” syndrome. Often during landscape design, people buy too many cute little plants in small pots and plant them too close together, too close to the house, or too close to the sidewall. This is particularly true with junipers. I repeatedly see one-gallon Chinese Pfitzer junipers planted right up against a sidewalk or house or in a two-foot median strip. These cute, one-gallon plants with a crown of about 10 inches will eventually grow to 4 to 6 feet in diameter, which will necessitate either their removal or heavy pruning or hedging. And hedge pruning usually wins. To me, nothing looks quite as stupid in a landscape as a single juniper that was planted too close to the sidewalk sheared to keep it from interfering with pedestrians. It’s not a focal point, it’s not interesting, it’s not a hedge… it’s a plant in bondage!
A practice of removing large branches from mature trees to control size is tree topping. Do not top trees or do not hire anyone who routinely tops trees! Tree topping is the drastic removal of large branches in a mature tree and the end result is truly awful to see. Topping leaves large open wounds which subsequently subject the tree to disease and decay. Topping causes such damage that the tree will ultimately die well before it naturally would.
Please perform some research before hiring an arborist. Make sure that whomever you hire doesn’t top by inspecting their previous work. Hiring a certified arborist should alleviate this concern.
Topping should not be confused with pollarding. Pollarding is a process where young trees are topped to encourage lateral branching and maintain a tree 6 to 12 feet in maximum height. Once a tree is pollarded, it requires consistent pruning to maintain. Older trees should never be topped or pollarded, and some trees do not tolerate pollarding at all.
Who Should Prune
As pruning goes, most of us just want to get away with as little work as possible, and I’m no exception. Don’t get me wrong, if I get a pair of pruning shears in my hand, something is going to get cut, but I don’t like to prune more than needed. I’m more happy to let a plant be natural than prune.
Pruning shrubs is easier than pruning trees. The average homeowner can usually prune a shrub without doing too much damage. Unlike trees, shrubs do not have a central leader. This form allows the average person to hone their pruning technique. In general, shrubs are more forgiving for neophytes to learn to prune.
I’ve killed so many plants in so many ways that one more herbicidal act by pruning on my part hardly affects me. If you are a homeowner with a limited number of “victims,” I’d guess you’re less likely to go for it. So here is my advice: When in doubt, don’t cut. Cut a little, wait until next year and evaluate the result or hire a professional.
If you are attempting to prune a large tree or remove large branches from any tree, I’d recommend the services of a certified arborist. Certified arborists know how to prune properly and know how to do it safely. I cannot stress enough how very dangerous it is to prune large trees. Besides the potential of just falling from large heights, you may cause damage to yourself or others when dropping a large limb, you can get entangled in power lines… the list goes on. However, if you are just removing small branches and dead wood, just remember less is more when you’re learning to prune.
When to Prune
Pruning can be done any time of the year. Optimal pruning times vary with different plants, and the best times to prune are in the late fall to early spring. Pruning is best in this time frame because the lack of leaves allow for better visualization of the branches; colder weather reduces the incidence of disease transmission, and damage to the plant is decreased. However, as the Japanese old saying goes, “The time to prune is when the pruning shears are sharp.” If you have a shrub or tree that needs to be pruned, do it when you can, but try to stay away from the late summer. The new growth that pruning stimulates may not have time to harden off prior to the winter and it may die.
Also be aware that pruning flowering shrubs can significantly reduce bloom for the following season. Shrubs that bloom in the spring, such as lilac, forsythia, and weigelia should be pruned after they bloom. These plants bloom on second-year wood or the wood that grew after they bloomed in the spring. If you prune the shrub before it blooms, you will be cutting off your flowers.
Now you are well versed on why we prune, when to prune, and who should prune. Next month I will be elaborating on how to prune a shrub properly. In the meantime, take some time to inspect your yard and evaluate how your plants have been pruned in the past and decide how you’d like to see them grow in the future.
Dianne Stortz-Lintz is a horticulturist and greenhouse manager for the City of Reno. For more information, call 224-1680. |
|
