Author Topic: Help! My Wisteria is Smothering Me! (Wisteria Pruning)  (Read 2148 times)

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Help! My Wisteria is Smothering Me! (Wisteria Pruning)
« Reply #1 on: February 28, 2011, 09:52:47 AM »

Wisteria Vines
by Cass Turnbull
“Wisteria is Latin for work.”  I wish I knew who said that.  But how true it is.  Under those beautiful color photos of arbors splendidly vine-laced and hung with glorious lavender blooms, there ought to be a warning label:  This Vine Can Be Dangerous, IT WANTS TO COVER...EVERYTHING.

Cisco Morris tells a story about the time he was house hunting.  He saw a home advertised for sale in the paper — three bedroom, two bath, on Queen Anne Hill.  The price was unbelievably low.  Upon arriving at the site he realized why.  Two ancient wisteria vines had overcome the home, actually lifting it off its foundation.  Their stems were as big as tree trunks.  I doubt it was an exaggeration.  I've seen wisteria rip off balcony banisters, smother entire trees, and everyone knows what they'll do to your roof and gutters.

I guess I didn't know when I planted mine against the railing of the covered porch eleven years ago.  But I'm not sorry, either.  Despite the work, there is nothing quite as wonderful as a wisteria.  I love the high excitement of watching the spring buds plump up and then expand.  It's so...erotic. Later, when it's in full bloom, I watch people point and sigh as they pass my house.  It makes my entryway look so...horticultural.  And it smells sweet.  In the winter the long fuzzy pods dangle down just above my head, as if asking to be petted.  And I must oblige.


I read a lot of pruning books. They crack me up.  I especially like the one that insists that you make your wisteria vine single trunked.  To do that, I think you'd have to guard it with a flashlight.  In reality, the main trunk is a combination of twisted and coiled stems.  They look like an unruly rope.  Wisteria just grow like that.  I don't know why they don't girdle themselves, but they seem to do just fine.

Espallier.  If you want to force side branching at a particular point (in my case I wanted the first set of scaffolds to train along the rail), you head-back (lop) the main stem at that point.  Two of the new shoots are then tied into position to become the scaffolds.  Or, as with mine, one became a scaffold, the other I shortened to about a six inches to become a “flowering short lateral”.  The third shoot, is allowed (or trained by tying) to continue up to become the main trunk.  Any other shoots are cut off completely.

Major scaffolds on a wall or lattice should be spaced at least 1 1/2 foot apart to allow room for the blooms to dangle down without running into each other.  All other shoots (runners) are either cut off completely (and there are lots and lots of these) or shortened to about six or seven inches (four or five buds) if they are wanted for flower production.  This is best done in the summer, with a follow up pruning in the winter (you can see because all the leaves are off).  Further shortening in the winter means that you cut back the chosen lateral to three or four buds.  This is similar to fruit tree training, to force vegetative shoots to become spur (flower) producing.  As with fruit trees, flowering is more prolific on horizontal branches.  In reality you will find that some of the shortened shoots set up flower buds, some die back, and some seem to be determined to be vegetative, sending out only long runners instead of forming a persistent spur system.  Don't ask me why.

Arbor or Trellis. In other situations, a wisteria vine is allowed to run to the top of the arbor or trellis and spread out as it desires.  Later it can be trained somewhat like a grape vine, annually cutting off fifty percent of the canes back to a few major scaffolds to keep it from getting too piled-up upon itself.  A preferable system is to painstakingly prune it like an espalliered fruit tree with “hands”, so that it has a beautiful winter branch pattern as well.  Whenever necessary, whack back any laterals that try to run off the sides of the trellis or threaten to climb into neighboring plants or structures.

I think that wisterias look best trained to an overhead trellis with the blooms dangling down from above.  Such an arbor or trellis needs to be very strong and sturdy.  Use 2x4s set on edge, at the very least.  Posts should be load bearing, not the flimsy lattice things you see for sale in catalogues or at garden stores.
 If the trellis is attached to the house, I strongly recommend that you plant the vine on the farthest post and let it fill in by growing toward your house.  You will be glad that you gave yourself that slight edge in later years as you find yourself tugging and tearing runners out of your gutters and shingles.

As a Standard or Tree. With the help of a sturdy stake or two, a wisteria can be trained into a sort of small free- standing tree.  This is commonly done in the south.  When the young vine reaches the top of the stake, whack it back to force it to bush out.  The resulting young shoots later become the main framework of the tree canopy.  The idea of the wisteria tree appeals to me since it can be situated in the middle of the yard, far from anything else.  There it can be vigilantly watched and pruned on all sides.


Finally, SUMMER RUNNERS With all wisterias, scores of runners will reach out into empty air every summer, hoping to grab onto a nearby helpless victim.  Cut them off before they strangle a sleeping dog or trip the gardener.  This can mean pruning every month if it is in your way, say on your front porch.  In any case, be certain to prune them off before winter when they harden off (stiffen and become woody, holding tightly to shingles, tree limbs, etc.) and are more difficult to remove.

Some runners I cut off to the trunk.  Most I whack back just to get them out of the way (to about five or six inches).  I do more detailed thinning and pruning in the winter when all the leaves have dropped off and I can see what's going on.

In the summer, my freshly pruned wisteria vine looks sort of like a feather boa, just to give you an idea.  By the way those runners can be used to make a tasteful simple wreath.  Just wind them into a circle.  Same with grapes.


UNDERPRUNING. The most common mistake is to not prune the wisterias enough.  Over 90% of the new growth (zillions of long, relatively leaf-less, skinny budded, runners) is cut off annually.  A single runner can grow twelve feet in one year.  After the framework is established, shorten many of the runners to six buds.  Remove the vast majority completely, every year!

RENOVATION. If it gets away from you or you have moved into a home that already has an enormous wisteria tangle, grabbing and strangling everything in sight, show no mercy.  Lop, saw and chain saw whatever is necessary to get it back down.  I suggest you cut several feet below where you want the regrown vine to be, since you will experience an upsurge of new shoots the following spring.  As with all heading cuts, the new growth occurs directly beneath the cut and heads up from there.  You will need some room to let it regrow over the next few years.  New growth will be vegetative (not flowering) and rampant for a few years.  I wouldn't be surprised if some major stems die back partially or totally, if you make cuts one inch or over.  But I doubt that you will kill the plant.  As some stems die back, cut off the dead bits.  Others will supply the replacement shoots to be tamed in upcoming years.

Wisteria blooming in the spring.

 Summer growth – Head back runners to 6" if they get in the way.

 Winter pruning – It's easier to see with the leaves off.

OVER PRUNING.  I didn't think it could be done.  But I have witnessed three novice pruners over prune.  Given a mature flowering vine, the pruner is tempted to remove too many of the flowering short laterals (I call them hands, because they are roughly the shape and size of human hands.  Very old vines have flowering short-laterals that are as long as arms.  These too should be left alone).  These “hands” have the fat flower buds that are reminiscent of fruit tree spur systems.  These fat-budded hands should be spaced about every foot or so.  They originate from the main trunk or scaffolds.  If they are pruned off or shortened too much the vine will appear sparse and have too few blooms.  The next year, such over pruning will result in a wild (wilder than normal) resurgence of flowerless runners.  The general idea then is to shorten or remove all the long, wild runners, and leave the “hands” to flower like crazy.

TOOLS.  My relationship to grapes and wisterias changed dramatically when I finally bought a specialized tool called a ARS long reach pruner.  No, it's not a pole pruner.  Its is light weight aluminum, with a trigger and a standard scissor type pruning head.  Some (interchangeable) heads have a sort of “grabber,” perfect, I imagine, for pulling tough runners out from under shingles and facia boards.  Such a tool saves hours of ladder work, but can cost about eighty dollars.  I got mine from the A.M. Leonard tool catalogue (1-800-543-8955).  The long reach pruner is only good for water sprouts and vines.  It lacks cutting power for thicker or woodier branches.  The only other tools required are loppers, hand pruners and holster.  Occasionally you may need a pruning saw.  Don't forget the twine and nails or whatever you use.

THE MOST COMMON COMMENT I get at classes and at the PlantAmnesty educational booth is, “My wisteria won't bloom.”  It is natural for these vines to take between three and seven years to start blooming.  I have read that frequent, proper pruning may help them to begin blooming sooner, or at least more.  On the other hand, some people have old vines that have never bloomed.  I am told that these are seed grown plants or “mules”.  I have often heard root pruning recommended to force an older vine to bloom.  Basically, this means that you use your shovel to cut the roots in a circle (or dotted circle) a foot or two from the vine.  I have also heard people recommend fertilizer formulated to encourage blooms, (not heavy on nitrogen).  However, I have been faced with such a vine and had no luck with either technique.  In that case, as with all non-performers, removal is the best option, and no one will blame you for it.

Link to illustrations to go with story:

The Pruning Book