Philadelphus is best pruned after it has flowered, usually in June. You can take out up to a third of the stems at the base. It doesn't need pruning unless it is outgrowing its space, though.

That is what I do. If you cut it all back at once it can miss a flowering.

Thank You, as I can now see I pruned it too early last year, thats why it didn't flower :o)
I was wondering if the one I have at the back of the summerhouse would be easy to dig up, it has been there a long time & quite big now, I would love to move it to where I can see it :o))

If its been there a long time (more than 4 years) and its quite large, its unlikely you'll be able to get the roots out intact to move it.

Thanks for the info Bamboo. It will stay where it is then lol the neighbour at the bottom of the garden won't complain about it staying there LOL, would it be possible to take some cuttings? x

Yes - semi ripe cuttings mid to late summer, grow on under glass.

Thank You again Bamboo. x