It’s March again, so it must be time for my annual haircut—er, for the shrubs and trees in The Garden, that is.  Woody plants are drawing near to the end of winter dormancy, and that means we’ve entered the year’s first pruning season.

But is pruning easier said than done?  Based on copious scene-of-the-crime evidence suffered by the hacked shrubs and whacked trees I see in our forest city, the answer must be “apparently so!”  True, true, but still a snob’s response.   Any of us can effectively prune well.  If we take the time to learn a few horticultural concepts, basic pruning becomes a pleasant exercise and beneficial service to our shrubs and trees, and easy enough to make a good job of it on the first try.

Certainly pruning has some subtleties, and every plant wants a unique, custom haircut. So, I simplify.  Every time I prune, I consider my four prescriptions: seasonal timing; specific plant habit; desired product; proper cutting technique.  These four prescriptions ensure that I think about all aspects of the job, and give the plant in front of me “its” cut.  Let’s go through the four prescriptions one-by-one.

One: seasonal timing.   A deciduous woody plant remains alive during the winter by slowing its metabolism to a near stop.  But in a few weeks, warmth and lengthening daylight will end dormancy and trigger fresh growth.   And this moment just before the end of dormancy is when we prune.  Why?  Wounds are open to disease and insects for only a short while before active growth begins healing them.  The plant has the entire growing season to respond to its haircut, set new wood, and look natural again by summer’s end.

Two: specific plant habit.  This prescription can usefully modify seasonal timing.  Some plants (maples, magnolias, birches) are “bleeders,” and will leak sap from pruning cuts for a couple of months in the spring.  This plant habit is the foundation of the maple syrup trade.  Bleeding reportedly does the plant no harm, but it doesn’t help (!), and it is also unsightly.  Instead, opt to prune these plants in late June.   They won’t bleed, and will still have enough of the growing season left to heal their wounds.

Other woody plants, especially our flowering shrubs, have the habit of blooming on “old” wood.  That’s wood that was grown as twigs the summer before.  If we prune these plants in late winter, we cut off all the year’s flower buds.  So, its best practice to prune old wood flowering shrubs just after spring’s bloom fades.  Then, they’ll grow new twigs, set abundant flower buds, and blossom vibrantly next spring.  A great example of this are the evergreen azaleas, which  can be sheared after blooming to within an inch of their lives, and flower like crazy again next spring.

Three: desired product. Why do we prune?  Are we growing a fruit tree or a topiary shrub?  Do we want a formal row of shrubbery, or do we just want to keep the lilacs off of the house?  So, we think about what we want the plant to be, but also think about what the plant will accept from us.  This prescription makes sure our pruning intentions don’t contradict seasonal timing and plant habit.  And taken together, the first three prescriptions build a f foundation for pruning with purpose rather than reckless abandon (as fun as that can be). 

Four: proper cutting technique.  This prescription is important because it recognizes how woody branches heal wounds, and guides us to make cuts that encourage quick recovery.  In brief,

• When removing a side branch, never remove any bark or wood that is part of the main branch or trunk
• Always cut at an angle that is “backwards-in-the-mirror” from the warty branch collar scar growing at the branch base
• And when cutting a twig, try to cut just above a side bud, and at the same slant as the bud
• Finally, use sharp tools, and make cuts that are clean, not ragged

These mechanics are also clearly depicted in the accompanying photos, and the technique can be kept as simple as that. 

I recommend a good pruning book to accompany the four prescriptions.  Find a book with numerous pictures, and a big species-by-species how-to list for the particular habits of our various woody plants.

Of course rules are made to be broken, and evergreens sometimes follow some slightly different protocols. More about pruning in the future, for sure. Otherwise, I think we’re ready to soak up some March sun, and give our yard its annual haircut.

And my own haircut?  Er, I can put that off until April, at least. 

P.S.: If you are interested in the biology behind proper cutting technique, find a book by Alex Shigo (he’s got a few, and they’re mostly interchangeable), or ask me, and I’ll blog about it.

Posted by Mark Bir

Tags: cleveland botanical garden, Mark Bir, plane tree, Pruning

This entry was posted on Tuesday, March 9th, 2010 at 9:25 am and is filed under Garden Tips, Mark Bir, Spring Gardening, Trees and Shrubs, Winter Gardening. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.