Technically, anything can be grown in a container for an extended period of time. I have a big collection of containerized trees and shrubs, mostly Japanese maples and conifers. One is approaching 25 years old and has never been in the ground!!

The key to doing this successfully is using a high quality potting media, an adequately sized container and the ability to unpot, root prune and repot and refresh with new media as often as necessary (usually every 3-5 years). There is also the additional complications of more careful watering required with a container, routine fertilization and what to do with it over winter. The roots are the most cold vulnerable parts of a tree or shrub but planted in the ground, the soil provides all necessary insulation. With a container, you lack that insulation and risk irreparable root damage of exposure to too cold ambient temperatures. You will need to find some sort of winter storage option.

but if it rings your bell.. dont let my opinion bother you ...to be changed every few years ... when you could do some root pruning ...

i had a WH once ... when i moved i potted 1625 plants to take with me .... but i left the witch hazel because it was one of the least inspiring plants i had for the 5o weeks a year it wasnt blooming ... and who in the heck wanted to walk out in a MI winter .. to look at the minimalist flower show ... lol ...

but if it rings yoru bell.. dont let my opinion bother you ...

now.. all that said ... you might be better off buying a smaller plant ... perhaps mail order ... and growing it on to size.. rather than buying a bigger potbound plant.. that might not be ready to stay in that pot forever ...

you dont mention how big the ones you are seeing are ... were they field grown and dug and potted ... etc ... there might be ... and there usually are.. many problems with large trees or shrubs in pot ... that are usually fixed when planted in other earth ... winding circling roots the usual suspect ...

but again... if its your dream plant... go for it.. life too short ...

ken

@gardengal48 (PNW Z8/9) Thank you for the advice. I have read that plants in containers essentially "lose a zone" versus in ground. Is this a good rule of thumb with witch hazels, too? Most I have seen are hardy to Zone 3, and I'm in Zone 5. Would I still need a winter storage option?

The US species are quite cold hardy but the xintermedia hybrids (like Arnold Promise or Carmine Red) and the Asian species are quite a bit less so.....zone 5 only. I would want to afford some sort of protection when temps start dipping into the low 20's or teens. Even wrapping the pot with bubble wrap can help.

One study using a variety of woody plants found a tendency for roots in pots to start dying back at about 20 degrees F above what it would take to affect them in the ground.

Name is 'Arnold Promise'.

GQT (if it’s the BBC programme) probably wouldn’t mention the risk of root freeze in a large container because it rarely happens here. It’s not really an issue. Things are pretty much as hardy in a pot as they are in the ground.

Floral, in my climate - much like yours - it's also pretty much a non-issue. Rarely does it ever get cold enough here for damage to roots of containerized woodies to be of concern. And that's true for even those of a more sensitive nature, like Japanese maples.

But there is a big difference in cold with a zone 5 winter compared to that of a zone 8/9 winter. I rarely see temps much below freezing, with the odd dip into the mid 20's(F) and then typically only for a day or two at a time. Zone 5 can easily see temperatures below zero. And sometimes for an extended period. I would want to have some sort of continency plan in hand for that possibility.

That’s what I was trying to say. Information from BBC programme wouldn’t necessarily translate to a z5 garden.