Osmanthus burwoodii
By Ashley48
Oxfordshire,
United Kingdom 
I have an Osmanthus burkwoodii which is nicely shaped but has got too large for the space it is in. It is about 6 feet high. Is it possible to prune it to about half that size and how should I do it? It has just finished flowering.
8 May, 2021
Previous question
« I have a clematis "Polish Spirit" (group 3 pruning). It's very vigorous...
according to the RHS it is pruning group 8
https://www.rhs.org.uk/advice/profile?pid=168
basically now as it has finished flowering.
Rejuvinating pruning is what you need to do and is often best done over several years, removing one-third to half of shoots to ground level, and reducing all other shoots by one-third in the first year. Over the next couple of years, each year remove half of the older shoots to ground level.
I have done this many times over the years with various shrubs successfully.
8 May, 2021