Mistletoe - how to grow it
When?
Do not sow berries from Christmas mistletoe as they are generally harvested when immature, and so will not germinate. Instead wait until March or April to harvest berries, when they should be white, plump and fully ripe. Berries for propagation will need to be covered on the tree to avoid bird damage.
What berries to use
There are many different strains of mistletoe, each preferring a particular host or group of host plants. Apple (Malus) and lime (Tilia) seem the most popular. Try to obtain seed from a host plant similar to the one you want to sow into for the best changes of germination. Harvest intact berries only, as if the berry skin ruptures the contents hardens, hindering germination.
Where to place it on the tree
Select a branch 10cm (4in) or more in girth on a tree at least 15 years old. If possible sow in the crook of a higher branch so that sufficient light reaches the seedling as it grows.
Method
Make shallow cuts into the bark, remove the seed coats from the seeds, and insert them under the bark flaps. Cover the flaps with hessian to protect the seed from birds. Sow quite a few seeds as both male and female plants are needed for berry production, and germination can be poor (generally only about one in 10 seeds germinate and produce plants). Male and female plants can only be distinguished once they flower, which can take many years.
Aftercare
As the mistletoe develops the host branch begins to swell. Growth initially is slow, the plant taking five years to reach berrying-size. If only all male, or all female plants develop more seeds can be sown onto the mistletoe itself as it readily acts as its own parasite.