It needs to be in the ground, in rich, well-drained soil in a sunny position and keep it well-watered.
You an expect it to be 4-5 years old before it flowers.
That pot is way too small to accommodate a climber that will want to grow to 30+ ft tall.

Hi, welcome to GoY, I agree with Urbanite, but bear in mind that it is from t&m, as far as I'm concerned the most expensive, rubbish plants you can buy, Derek.

Thank you Urbanite and Derek for your replies. The plan was to train out into a tree and then just keep giving it bigger pots. My main concern is that the wispy bits have never developed on it, the plant has never increased in size. Just produces more leaves. It was a bare root plant and once planted laid dormant for about 5-6 months. Could it be a dud plant?

As Urbanite has already said it isn't going to do anything in that pot. Get it into the ground and remember it will need something to climb up.

And mine doesn't look like a vine, it's never produced any vine like growth. Just leaves and Bush like.

Yes poor thing shouldn't be in a pot, that's why you haven't got any vine like growth.

Okay thanks, I'll figure out where to put it in the ground.

Rebecca do be aware that that the wisteria will grow very, very big and need something serious to support doesn't grow on up without something to climb against.

Okay thank you, I'll figure something out.

Take a look at the T&I'm web page http://www.thompson-morgan.com/how-to-grow-wisteria which will help you. The one thing not mentioned is the size of the planting hole which needs to be 2-3 times wider than the rootball and at least 1 1/2 times as deep. If you have a heavy clay soil you need to dig deeper and wider to avoid creating a sump around the roots where water will collect.

You need to plant the wisteria at the same depth as it was originally (if you can remember? Did you add any soil/compost to the top of the pot after planting? If so, you will need to remove that)

Part fill the hole with good organic material mixed with gravel (to give good drainage). Plant the wisteria to the right depth and backfill with good organic material.

keep it well-watered July-September (but don't let it get waterlogged) when next year's flowers are formed. But be patient it may still take several years for it to flower.

And, as Moongrower says, it needs something to climb up. - which is best sorted out before the wisteria starts growing.

Thanks urbanite. It was a bare root plant, so I don't know the soil level. Any ideas?

Look for the graft - it shouldn't be buried.