Posted: 26/01/2015 at 09:36
If you cut the top out it won't be a Christmas tree shape any more - it'll look like a bit of hedge
It should be potted in a large pot in soil-based John Innes compost - I'd use No. 3 with some added grit.
Keep it in a sheltered spot where it gets some sun and some shade, and turn it around by 90 degrees each week so that it gets even light and grows in a uniform shape.