It's almost impossible to kill a wisteria! So I don't think it matters when you do it. But it's hard to believe a 12-15 year old wisteria is small, even if kept cut back. There is likely to be a huge, widespread root system there and you are likely to get new vines coming back from the remaining roots after you have transplanted what you can. (Are you sure you want to keep it at all? If you haven't done much with it in 12-15 years, it might be best to just do your best to kill it off and move on to something else....) Do you know what kind of wisteria it is?

Is it American Wisteria (W. frutescens) or an Asian variety?

The naturalized Asian species, most of which are Japanese-Chinese hybrids, are hard to control and considered invasive. Thus, they should not be planted near homes, decks, etc. as they can quickly get out of control and threaten the integrity of the supporting structure.

Most wisteria sold in nurseries is the American species, which is much better behaved. A quick way to distinguish them is that, unlike their Oriental cousins, the American species leafs out before flowering. My sources say that the American species resents transplanting, but it is a vigorous enough plant that I think it would be okay if done with some TLC. It would probably be best to transplant after hard frost danger has passed in Spring. Try to get as much of the root structure as possible (which is very difficult because the roots tend to be widely dispersed, easily breakable, and extremely long) and keep the ground wet for several weeks in the new site so the roots can recover.

This post was edited by mistascott on Sat, Jan 19, 13 at 12:08

I have no idea what kind they are. I planted them from seed I got from the lady next door. The biggest one bloomed a few years ago. They send out 8-10 foot runner/sucker shoots from the base every year, but I always cut them off. They are in a bad location and I didn't want them to grow up the house. If I can move them I would like to let them grow this year. I would like to prune and train them heavily so that they stay fairly compact and can eventually hold themselves upright would out much support...I don't know, we'll see how they do.

I don't remember if it sent out leaves before the flowers or not.

I should be able to dig out fairly far from the plants to get as many roots as I can.
How far out and how deep should I dig?

Here is a photo of them. They really are that old. Not the greatest photo, but you can see all three of them. The photo got very blurry after I uploaded it. It should be much clearer than that.

Based on the gray stem color and your description of 8-10 ft. suckers, you likely have an Asian wisteria of some sort. Those are no fun. They can't really be kept in an ornamental garden without prohibitively frequent maintenance. They will quickly outgrow and collapse any support structure. As they are vines, they will constantly search for something to support them if nothing is provided, which means they could end up taking over nearby trees. If I were you, I would get rid of them (this is a formidable task given their vigor) after confirming they are indeed Asian wisteria this Spring. American Wisteria is a much more manageable alternative -- it lacks the fragrance of the Asian varieties, but this is more than overcome by its relatively compact and trainable growth.

This post was edited by mistascott on Sat, Jan 19, 13 at 12:36

It is certainly possible to grow the Asian wisterias in a controlled manner - but it does take diligent pruning. If you are not prepared to do the necessary pruning, you should not grow them! And I would only grow them as 'trees', in a spot where they cannot easily latch onto something and where it's easy to monitor for and remove root suckers. Also, remove all seedpods after the leaves drop, so they won't seed around.

The picture below from May 2010 shows our Chinese wisteria 'tree' (ten years old at that point) and the young Japanese wisteria (3 years old in the picture - it bloomed for the first time in May 2012). They do need sturdy support, even when grown as trees, if you let them get any height. Both of ours needed supplemental angle-iron supports at 5 years of age. A Chinese neighbour keeps her 'trees' very small and tighly pruned and has - so far - not needed support for them. I do not follow the standard pruning guidance. I prune all whippy new growth back into the desired framework once the growth gets more than ~12-18" long. At peak growing season, pruning is a weekly - sometimes daily - task!

Our wisteria 'trees':

{{gwi:36064}}

A closer view of the Chinese wisteria (with a young friend perfectly color-coordinated with it!)
{{gwi:11742}}

A neighbour's small 'tree':

{{gwi:193459}}

Excellent pictures, woodyoak. Thanks for sharing! I can barely keep my American Wisteria in check so I can only imagine an Asian one (though you are in Zone 5, so it might be a little more manageable than trying to grow one here).

Wisteria look particularly nice when tree-trained, but it is much easier to tree-train a fresh specimen from the nursery than an established planting. It can still be done, but will take a bit more work and time. I wouldn't transplant and tree train/prune all in the same season to minimize shock to the plant. Also, be 100% committed to the diligent maintenance required!

Asian wisterias get a bad rap in the South because they have escaped into the wild and are doing a number on our native forest succession. I suspect they are not quite as much of a nuisance in the Midwest due to the shorter growing season, but if you live near a wooded area and sell your home, please either get rid of the wisteria or inform the new owners of the need to be diligent about keeping it under control.

This post was edited by mistascott on Mon, Jan 21, 13 at 19:19

woodyoak,

Thanks the the photos! That's exactly what I would like to do with my wisteria.
Can I plant all three of them together! I didn't know if they would strangle each other.

Wisteria doesn't seem to strangle itself - when it twines around itself the stems seem to eventually just grow together and become one trunk. I'm counting on that to happen to make a sturdier trunk for the Japanese wisteria. I wound multiple stems around the original support stake - it'll take years for them to merge totally but it makes for an interesting look! You can see the look in the picture below - that's also the first flowers at five years in the garden....

{{gwi:158153}}

Here you can see a stem that twined around one part of the main trunk structure of the Chinese wisteria a few years ago - we didn't notice it when it happened. It doesn't seem to have had any impact on the tree. The vines are so vigorous that, even if a part of it died off, you could just cut off the dead bit and train in new growth to replace it!
{{gwi:193460}}

The important thing is to think about how you want it to look and then prune, prune, prune to control and shape it! I really recommend planting it somewhere where you have easy access to it from all sides to prune and remove root suckers - never let the root suckers grow or it's too easy to lose control. (Ideally, dig down and pull the sucker off the root - that may remove the budwood that gave rise to the sucker. Cutting off the suckers - whether they are on the roots or the trunk - is less effective as new sucker will originate from the same spot....)

Try not to let the 'tree' get taller than it's easy to reach to prune. You're more likely to do the pruning if it is easy to do! We took 12-18" off the top of the Chinese wisteria tree last spring because it was getting out of easy reach of the long-arm pruners we use to snip off/cut back the new whippy growths. See link below to the pruners we use. We keep them in the garage so they are easy and quick to go get when we see a growth that needs pruning. The easier it is to do the work, the more likely it is that you'll do it!

Here is a link that might be useful: long-arm pruners

woodyoak,

Thanks again for all your advice!
You have just described what we do when pruning the apple trees at the orchard where I work. Lots of root suckers come up every year that need to be cut out, we always take the height off the trees to be able to reach them and as old wood needs to come out we train new branches to take there place. I have lots of open space for my wisteria far enough from the house so there wont be any home invasion.

I might buy a new one this spring just to have a strong start and still keep my 3 little ones. I hate to get rid of them - I did start them from seed and they bloomed once a few years back, so I know what they are capable of. I've had them long enough that I hate to give up on them. Not very many people can say "I started that wisteria from seed and look at it now!" I still live at home with my parents, so I might just get a large pot to plant the three "seedlings" in so I can take them with me when I move out in a few years. I might even treat them as a large bonsai.

Wisteria is a common subject of bonsai - try doing a Google image search on that. There are some amazing wisteria bonsais out there!

A couple of other pieces of advice:

They need very sturdy support. Both of ours needed additional support at the five year point. Not long after the Japanese wisteria bloomed this spring we got a windstorm that broke the wooden support pole off at ground level! The wisteria is now supported between two angle-iron posts painted dark olive green and connected together with metal tie rods that also run through the remains of the wooden post (which can't be removed as it it tightly gripped by the twining stems!) The Chinese wisteria was originally supported between two lighter metal posts but also needed an angle-iron support as a sort of third leg at the five year point. The regular pruning makes for a dense, bushy plant that gives the wind a lot to push on! I recommend that you use one or more sturdy angle-iron supposts when you plant a wisteria. I'm a member of the RHS (Royal Horticultural Society in the UK) and I remember reading an article on wisteria in the member magazine that said almost all Victorian-era surviving wisteria trees have an iron stake in the middle of their trunks (i.e. the tree has engulfed the stake - so one needs to take care if sawing down an old wisteria tree!)

The other piece of advice - always remove any seedpods you see - easiest to see after the leaves drop... Otherwise in the first warm days of spring the pods will open explosiively and fire seeds around! So you'd then have seedlings to contend with. (I did a germination test on the first seeds the Chinese one produced - I got 25-30% germination after the pods had spent the winter on the tree....) So now I make sure that I remove all seedpods.

It sounds like you have a good background for pruning and training a wisteria. Good luck....

After the windstorm:
{{gwi:158250}}

Standing up again:
{{gwi:158262}}

Same advice as others have already put out there, just wanted to add that transplanting shouldn't be a problem. I moved mine sometime really late in the year (november?), it ended up being bare-root when most of the soil fell off, next spring a late freeze killed every last flower and foliage sprout, it resprouted in June and then went on to flower in July.... and I never did water, even with a very dry spring. I guess you can see how it becomes invasive!

Unless I'm trying to gain some height or width I usually trim back every sprout to about 3-4 buds during the summer. This needs doing about once every 2-3 weeks :) I never prune in the winter even though most sources recommend it.
Here's my shrubby tree last summer after its winter transplant ordeal. Please ignore my unmown "wildflower meadow"

I have two, two year old Japaneses Wisteria growing in front of my home. They were placed in a bed with metal decorative pares. Which has Flimsy metal acorn decorative in between. The Wisteria trunk has grown into the flimsy part of the pliers ( these really are not pliers just metal). And now my husband has decided he wants them moved. First can I transplant them. They have not bloomed yet) and I am afraid if we move them it will take even longer to bloom. Secondly if we do move them, What kind of frame am I needing for stubilty. Are these also so invasive and will need as much pruning as the Chinese Wisteria? My e mail address is debbyfain1969@gmail.com and would love your insight in this matter.

I find our Japanese wisteria needs far more pruning than the Chinese one! The Japanese one is still producing many root suckers that need to be removed every few weeks and the new whippy stem growth on the top grows at a furious rate - both in number of new stems and the speed at which they grow long. The Chinese one stopped producing root suckers more than 10 years ago and only occasionally produces new stems on the main trunk - those stems are removed when they become visible after the leaves fall in the fall. The Chinese one does produce lots of new stems but they are both fewer in number and slower growing than on the Japanese one. The Japanese one - which is 7 years or so younger than the Chinese one - produces lots of new stems on the trunk which are removed when the roots suckers are removed. Pruning wisterias regularly, in my experience, promotes flowering growth. Both our Chinese and Japanese ones flowered after 5 years in the ground.

I doubt that transplanting them would do much harm.... What kind of support you need will depend a bit on how you want to grow them - e.g. as free-standing 'trees' or as vines on a pergola. We grow ours as 'trees' and, after initially providing insufficient support, support them with angle-iron posts sunk into the ground and connected with metal tie rods. You can see the Japanese one suspended between its supports in one of the pictures above. I prefer the 'tree' approach as it makes pruning easier than if we had to climb around on a pergola!