TREE AND SHRUBSLeaf it to me

I planted a hedge of15 holly shrubs 8 yrs ago,6 shrubs in this hedge have hardly grown,why?

I work in Landscape gardening, I passed the garden in question and spoke to the owner.
The plants have bben weatered,pruned & fed regualarly.
The shrubs appear to be the same Ilex aquifolium,the aspect is OK, & holly definately grows very well in this area, some of the shrubs do have slight ‘die back’.
The laves are not healthy and smaller than the healthy hedge.
I real mystery.

When in doubt, get a soil test performed from your county extension. Let them know what plant you have so they can give you the proper test results back to show what nutrients are needed for that species. Then apply the amendments. It will take the guess work out of it and then you will know why they are not growing. You may want to also take some samples of the the plant to them also to see if there is any kind of disease or insect that may be causing the problem. Good luck. Pictures would help also.

Giroud Elevates Overgrown Holly