How can I nurture my wisteria plant so that it blooms?

See if this helps.

https://homeguides.sfgate.com/long-before-wisteria-plant-blooms-first-time-69737.html

https://www.gardeningknowhow.com/ornamental/vines/wisteria/wisteria-blooming-problems.htm

https://forums.botanicalgarden.ubc.ca/threads/dispelling-some-myths-about-wisteria.25944/

Maybe try a fertilizer like bloom booster from miracle grow

If there is grass close to the stem and out to its growth width it should be removed. Once that is done a bit of Epsom salts would do it some good. Water.

Sometimes it takes an exceedingly long time for wisteria to flower but once it does it usually gets better and better {mine did}. Also, if you live in a wintry area burlap can be a wisteria {and other plants} best friend. It isn't the snow that kills so much as it is the wind. We tend to forget that wisteria is mainly a warm sun loving plant even though it tolerates our Northern clime. Be sure to have a very, very strong support for it as the plant gets exceedingly heavy unless you trim it down and shape it like a tree when it has a thick "trunk" {normally accomplished by loosely intertwining the vines and keeping them trimmed of green growth and even flowers. Be careful of fertilizers. They can cause you to get more green than flowers. NEVER let it go dry while it is growing for the first few years. I noticed your's is 5 years old so it should be okay by now ~ meaning the roots should be deep enough. If it doesn't rain for a week and you have younger wisterias, water deeply. It and most other plants will thank you.

Give it Calcium and through some steel nail so they rust slowly for the iron its probably lacking..