I planted a philadelphus in 2007. It struggled for couple of years as the garden had been site of old stables/garages/dumping ground - though I did dig out a hole and put good stuff in. Then hubby, being helpful, gave it a severe pruning 'to tidy it up' at the wrong time. So it struggled a bit more. Last year it looked good though no flowers. This year looks good - and huge - with just one little spray of flowers. I have told it that if no flowers next spring it is coming out! It is, unfortunately, the large variety. Any suggests as to what is going wrong please.