Simple steps for caring for a pot grown tree:-
1) Over the Christmas period the tree must be watered. I like to place in in a plastic hole free clear pot liner inside a beautiful earthenware pot but still in its plastic plant pot. Choose something rustic. You could just disguise the plastic liner with festive paper. Don't forget the liner because you do not want muddy water all over the carpet. Liners come in a range of sizes and can be trimmed easily. Try and avoid standing the tree in front of a hot radiator or next to the fire and other obvious places that will dehydrate it.
2) After Christmas it can be planted in the garden. Our British growers planted them and grew them in pots which they buried in the ground. You can see where the roots protruded from the holes in the pots and had to be trimmed back to lift. You may wish to keep the tree in the same pot for the first year and bury it in the ground so it will stay more moist and not rock about.
3)Dig a hole and put it back in the garden. At some point in its life you may need to cut the pot off the roots and pot it into as slightly larger pot but not too big to get in the house at Christmas time.
4)Give it a seaweed feed in the spring as the weather warms up and plants begin to grow and do not let it dry out as this is fatal for fir trees.
5) Prune in June to shape or you may end up with a wonky tree.
As you see keeping a sustainable reusable tree is low maintenance but not no maintenance. At some point you will need to re pot it into a larger container using a good rose tree and shrub compost.
Link to 2019 British Christmas tree prices