I have a wisteria vine. I live on the east coast. Should I cut it back now(Dec) or wait until the spring? Or should I not cut it back at all?
It is best to prune these in mid-winter, or in summer. You will want to do this when there are no blooms on the plant. This article will give you more information: https://www.gardeningknowhow.com/ornamental/vines/wisteria/pruning-wisteria.htm
I have two wisteria bushes next to each other. One leafs out earlier than the other and looses it's leaves sooner than the other. It's been a month since the leaves haven fallen off one bush and the other still has a large portion of yellow/green leaves. What seems to be the problem and if so what can I do?
This could be a difference in microclimates between the location of the two wisterias. One might be exposed to slightly more sun or warmth earlier in the spring, causing it to leaf out earlier. The other wisteria would then be behind its schedule for the etire season. I don't think this would be harmful, though. Here are some other reasons the other wisteria may produce its leaves late:
https://www.gardeningknowhow.com/ornamental/vines/wisteria/wisteria-no-leaves.htm
Shall I dig up and pot again?
These can take up to 15 years to set bloom! It may be that it is just not ready yet. I fear that digging it up again will only stress it, which will prolong flowering even more. Here is an article that will give you information on the subject: https://www.gardeningknowhow.com/ornamental/vines/wisteria/wisteria-blooming-problems.htm
How much can I cut back on an old overgrown wisteria vine that has never been cut back or trimmed ?
We had a wisteria Growing up a tree in the backyard. Every 7-8 years, we would cut the vine back to 1 or two feet, and it would very quickly regrow and cover the tree.
My American Wisteria is growing up a pergola. It is 3years old. It has a bunch of vines winding up the pergola - not one big thick one as I see in pictures. What should I do?
These take very long time to get that big. You can't really help it out much, other than giving it proper care until it reaches maturity.
This article will refresh you on the care of this: https://www.gardeningknowhow.com/ornamental/vines/wisteria/growing-wisteria-proper-wisteria-vine-care.htm
Is it safe to burn a large amount of Crown Galls from our Wisteria or is there a possibility of spreading the infection? We live in a rural area where burning is permitted and take care of some storm damage in this fashion.
Yes, burning is considered a good way to destroy crown gall-infected plant parts to prevent the spread of infection.
http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/crown-gall/
Can you deepen the purple color of a light violet wisteria with fertilizer or some soil additives.
Not usually, no. This will be determined by genetics. If they are older, then they may naturally lose color over the years. They will, more than likely, over time end up lightening up even more. This article will give you more information on the care of these: https://www.gardeningknowhow.com/ornamental/vines/wisteria/growing-wisteria-proper-wisteria-vine-care.htm