Posted: 27/11/2014 at 17:41
I asked this question about this time last year or the year before. This was my answer, Unfortunately I can't remember which David posted it
But this is it, my lesson in evergreen cuttings
This is really a good time of year for evergreen cuttings as temperature are low and hence the danger of your cuttings drying out is much reduced. Cuttings should ideally be about 6-7" long with a square cut at the base with a sharp knife or secateurs and only the top two or three leaves left on the cutting. A free-draining compost is best (add sharp sand or perlite) since the cuttings should not dry out but do not need to be water-logged as this can cause them to rot. Raising them in a largish plant pot with a clear plastic bag covering them seems to work quite well, watering as needed. They will not start to grow until the Spring at the earliest and may not root properly till the Autumn or late Summer. If they start to show some new growth that's a good sign that roots are forming. The cuttings should grow vertically with perhaps a bit of support from a stake although there is likely to be some side growth. Select a strong side branch and prune away the others cleanly with no snags. If there is no obvious strong leader shoot the tie one of the stronger side growths to a strong vertical cane to encourage it to grow upwards. Add more ties with soft twine as it grows, preferably firm but not too tight. Trimming these side branches off as the plant grows will encourage it to grow a strong central stem and you can cut back the leading stem at the height you wish and form a lollipop shape or grow to a full sized tree if it grws unchecked. Alternatively, trim the side branches into a cone or column shape if you prefer. Tying the plant to a vertical stake as it grows will help to keep it straight but it helps to put some padding (rag or an odd piece of foam rubber) between the stem and the support to stop chafing the bark against the stake.
I think that it would help you a lot to get a copy of the R.H.S. Propogating book. possibly second-hand via Abe Books etc on the internet. It lists techniques for growing a wide range of plants from seed and cuttings as well as grafting. The Pruning book is excellent too. All the R.H.S. books are worthwhile come to that and quite cheap in paper-back.
You can see some excellent examples of topiary and ornamentally trimmed hedges in many old country houses and places like Westonbirt Arboretum are well worth a visit.
I hope this is of some help.