I have a fairly small conifer, which is currently about 4 ft high. It was
until recently kept in a pot, but a few months ago I planted it at the
bottom of the garden.

I know would like to bring up to the front of the garden to fill a space I
have, but I am concerned about future growth of the roots as the plant would
be nearer the house.

If necessary I would put it back in a pot, but was wondering if there was a
safe way to plant it in a pot with the pot underground, so it looks like it
is planted, but with the pot restricting root growth. Would this in fact
restrict the root growth or would the roots just end up spilling over the
top and outwards? I'm not concerned about restricting the growth of the
conifer, as I don't want it getting too big anyway.

Any advice appreciated.