I planted a new ligustrum ovalifolium hedge at the bottom of my garden in the spring of 2012. The plants were bare rooted and appeared to be healthy when I put them in. Some of them have taken quite well and are nice and green, however others have had very little growth and now have quite purple leaves (see attached pic.).
I haven't really used any fertiliser on these, apart from a very small amount of potassium fertiliser that I was given. I presume this isn't the problem, as I have applied it to lots of other plants in my garden in a similar quantity, and they are all otherwise fine. However, I have now stopped using this just in case.
My garden is next to a river in Cumbria, and the soil appears to vary considerably ranging from a clay layer close to the surface up by the house through to being much more free draining down by the river. The purple privets in question are close to the river, and the area can flood on occasion. It has also been a very wet summer here. I've not had any soil analysis tests done, but I have a suspicion that parts of the garden are short of something, but as I'm entirely new to gardening I have no idea what. The area affected is in full sun, so it's not light - in fact, the plants in the shade are doing a lot better.
Might it be a nitrogen deficiency or something like that?
All suggestions welcome!