Many things have been written a about this most beloved of parasitic plants. I’ve been working in a couple of gardens with newly establishing clumps, one hand sown, one bird sown.
So how does it work?
In the wild the berry passes through the bird and is deposited (ok, excreted) on a suitable host tree. There are many suitable hosts but the favourites are Apple, Hawthorn, Poplar and Lime (Malus, Cretaegus, Populus, and Tillia for latin lovers). Once deposited the sticky glue of the berry (mostly remaining in tact through the digestive tract of the bird) holds the seed in contact with the branch long enough for it to begin germination.
Growth is SLOW. Once attached to the host plant leaves will appear the following growing season. But as individual shoots produce just two new branches per year with one pair of leaves at the tip of each it’s quite a wait until berries arrive, 4 years, let alone enough for a decent bunch for the Christmas festivities.
If you want to bypass the bird method you could try smearing berries, fresh and ripe (white) are best, directly onto the bark of a suitable host branch (minimum 20cm diameter). Start with at least a dozen berries. Best not to score the tree as wounds can introduce disease which weakens the tree. Remember this is a parasite so it will weaken the tree and any fruiting will likely diminish somewhat.