By Jennyr
United Kingdom 
A few of my new shrubs are getting yellow leaves which then fall off. I've read it could be drainage. If so do I have to dig them up and re-plant. The only confusing factor is that an established mahonia, many years old, and some ivy have also developed yellow leaves which have fallen, (in the same border) what could be causing this?
7 Jul, 2014
Answers
when you say new shrubs, how new are they? Planted this year? And is your soil heavy, sticky clay? What part of the UK are you in?
7 Jul, 2014
For the ivy and mahonia, they may just be following the pattern you get with most evergreen shrubs, which is that as or after the new leaves grow, a proportion of the older ones are shed.
I've got a viburnum and a holly that shed daily from May into July, just enough leaves each day to be annoying. I've got several camellias that shed in April and May, the leaves going bright yellow before falling. And I've got a couple of rhododendrons which have just started to do the same.
If it's deciduous or herbaceous plants I'd be a bit more worried, maybe dig'em up and put into pots for a few weeks while any problems in the soil for drainage or drought get addressed.
7 Jul, 2014