Interesting guys... I have a different opinion... OK I have a couple huge wisterias growing my back
yard. We trained them up over the patio cover for the last 20 years, and the thing was gonna try to rip our patio cover down so I cut it all the way back to the stump this fall. The stumps sit at about 8" thick and 4 feet tall, and they are not harming anything anymore.. They are sending out a LOAD of new shoots, LOTS of new growth, and I know the roots are spreading through my tiny 4' X 50' forest garden, but I LOVE IT! Because they are in my zone 1 location... literally IN my garden, so everyday, I get to rip off lots of long green vines and leaves, and drop that down as mulch under my plants. It's one of my favorite things to do in my garden. I have all kinds of other things growing right around the stumps too, so veggies seem to grow right on top of the wisteria roots.
I can see the
root system is expanding but the way I see it, I'm simply getting more and more organic matter into my soil, and more nitrogen fixing. Someday those roots will be dead and decomposing down there. Thats a great thing right?
So as long as its in zone one where I can keep chopping and dropping, I can't think of a better nitrogen fixer for the garden simply because it produces so much nitrogen rich biomass. Out in a zone 3 or 4 I would discourage it because it would probably spread out and take over everything... in 20 years you would have a wisteria forest... REALLY SUCH A BAD THING??? But as for a zone 1 veggie garden I say YES grow that! In the ground or in a container your choice... I prefer in the ground where they put roots down and
feed the soil from below as well as on top.. it produces so much biomass.
Also it's so trainable you could probably make living furniture out of it... or head pieces.. it's useful! I see it as a blessing not a curse. I think a lot of
people who see this the way I do will appreciate this plant and I am propagating them from
seed and cutting to offer for sale in my little backyard nursery.
So in conclusion, I think it's a great chop and drop biomass producer and nitrogen fixer. High maintenance tho so keep it in zone 1 or 2, maybe contained...