No, they are not really that blue and soil makes absolutely no difference. I would recommend always seeing a Wisteria in bloom before buying if you can. You then know the true colour and have proof that it is capable of flowering. Wisterias grown from seed can take years.

Very invasive. Please consider native wisteria.

I read about the invasiveness. person who wants to grow it is a somewhat serious gardener and would maintain its size but I don't think it's that blue.

the website replied already:

Hello, Thanks for your interest in Nature Hills Nursery. Our Blue Chinese Wisteria blooms feature a dark purple bud that opens to a lovely icy lavender and purple flowers, and fades to blue as the flowers age. As the flowering season progresses, the oldest blooms fade to that magnificent blue that people just love. Unfortunately, it doesn't work like a hydrangea to be more blue with acidic soil.

Native wisteria can also be very invasive.

"Native wisteria can also be very invasive."

Sorry, but that is pretty much an oxymoron. Native plants are almost never considered to be invasive. The accepted definition limits that to non-native exotics. Aggressively spreading, perhaps. But not invasive.

Also, tree form wisterias tend to be more closely managed and controlled than a rampantly growing vine.

" Native plants are almost never considered to be invasive"

Maybe not where you live, but wisteria will spread all over the ground and trees in the South, smothering everything in it's path. I've personally seen what it can do in a short time, if not constantly kept in check.

Neither of the two US native species are considered invasive by any definition. And a true invasive species is almost always going to be a non-native exotic species.

"The most commonly grown ornamental variety is Chinese wisteria, which while lovely, can be invasive. A better choice is its cousin the American wisteria (Wisteria frutescens). Growing American wisteria as an alternative still offers the elegant blooms and foliage but in a native, non-invasive form."

Non-Invasive Wisteria 101

woodrose, The wisteria you are seeing is NOT the native wisteria, It is the invasive Chinese. You can tell them apart, but it is hard from a distance.

I think woodrose’s point is vailid. ANY wisteria can be a rampant grower/seeder if it is not controlled. And that = invasive for most people, regardless of what the technical definition of invasive is! We grow both a Chinese wisteria (supposed to be ’Blue’ but certainly isn’t blue…) and a Japanese one (which is also clearly not the variety it was supposed to be…) but have kept them well controlled for all the years we’ve grown them (22years in the case of the Chinese one and 15 for the Japanese one). The big problem I see is that most people do not know how/are not willing to do the work required to keep them (even a native one) in check! When we sell here eventually, the odds are high that the house would be a tear-down and the wisterias would likely be removed.

Well, the one I am seeing in North Alabama at the top of the pine trees on my street, is the Chinese invader. The native is not a thug. Canada has no idea what Alabama is like.