The roots will circle and strangle the tree, some will root into the ground out the drainage holes, it will croak eventually.

Unless you plan on treating it as a bonsai (including the routine maintenance prescribed by bonsai technique), your tree should be planted very soon after purchase. Leaving it for more than a few months is likely to cause problems. Potted trees need to be potted up to larger pots pretty often and potting medium must be renewed on a regular basis, if you are going to hold them for more than a few months.

My mother bought two Quercus lobatas 21 years ago from a native nursery. For a decade they were in 2-gallon black plastic pots in California. These poor little valley oaks served an eleven year sentence in plastic prison but apparently had some water when the warden watered her orchids nearby.

Ten years later in 2004 I found them in the backyard. One was placed on a patio. The other was placed inadvertently on top of soil and the roots had gone through the pot and into the ground. The one that had taken root had a trunk and was 6 feet tall while his brother remained a 3 feet plant. I took a lopper and cut the one inch diameter root and transplanted the two into 5 gallon terra cotta pots not expecting too much from them and kind of freeing them to rest in peace.

Both did fine in their pots for about 5 more years until 2010 when I noticed vigorous jasmine shoots nearby slowly strangling the taller older brother. I freed the older brother from the fragrant flowering vine and persuaded my sister and reluctant brother in law to adopt and plant him in their front yard. His younger twin brother stayed in the pot without any grumbling and put out new leaves every spring but never grew much.

My parents moved into a home after my father had a fall. No one lived at the house and the potted one died. My father followed a few months later. The younger brother must have been really jealous of his older brother who found a family in the latter years, but before that their dispositions were opposite. He had a sunny location where rain could fall and help him make it one more year while his older brother was in a coma covered with jasmine in a shady corner of the deck.

The oak with a severed tap root after a decade in a black pot is now over 20 feet tall with a 5-6 inch trunk. He went through some hard times but birds now chirp while perched on his bouncy awkwardly gangly branches.

How long can trees remain alive in a container? 450 years or more with care as I saw a recent bonsai cedar that old at Happoen in Tokyo. They'll be happier in the ground though.

pots in winter in the great white north.. are much trickier to deal with.. than in the more temperate areas ...

i dont know where you are ... but i am sure roses offering is limited to peeps in similar circumstances ...

the bottom line is water management ... which involves not only water.. but the specific tree itself ..... the media.. the pot size.. how water drains .. and your ability to micro manage it all ... and that is why.. bonsai peeps can do what most of us cant... heck.. their trees spend more time out of media than in it.. just thru the process of bonsai [not really, but you should understand the idea, if you know anything about bonsai root pruning]

BTW.. a 5 to 6 foot tree ... permanently potted.. should be .. i am guessing.. in a 25 to 50 gallon pot ... and i will bet dollars to donuts .... you wont be buying it in more than a 5 gal pot ... and therein lies the rub ... and the potential to fail ....

ken

If you prune the roots you should be okay. Woody roots are to anchor and support the tree. If left unpruned the pot will be a mess of intertwined woody roots. But if you trim them new Roots with root hair will grow. They are the ones absorbing moisture and nutrients.

I think it depends on the tree and container. I've seen four foot tall deciduous trees in really tiny 1 quart pots sold by home depot or online retailers. I doubt they'd last long. I've also seen small trees growing in big pots sold by a local native nursery/botanical garden/ I imagine they'd last longer.

I routinely buy small trees in pots from the native nursery's sale and keep them on my deck until I visit my parents. My parents routinely buy pairs of potted dwarf alberta spruce from Home Depot and and keep them on the deck for 6 months or so, then plant them in the ground. They often survive.

If you never remove it from the pot,it usually becomes root bound. It may or may not actually strangle itself with encircling roots. Also, a small pot can't hold much water, so you'd have to water it a lot. Oh, and if you are keeping outside in the winter, make sure it''s something that can survive one full zone colder then yours...a tree in a pot has less insulation around it's roots then a tree in the ground. (As I learned with a small potted Rose of Sharon in Zone 5 or 6).