Ilex aquifolium variegata
We planted 3 along the west side of a fence on east side of our backyard. They were 5' tall at the time of planting in fall 2009. I know they are slow growing but we planted them for privacy reasons and accepted the fact that they'd grow maybe 1-2" per year. They get enough water...approx 6-8 hrs of sun...ph has been measured at 6.3...and we fertilize with holly tone and mulch in fall. Leafing is not particularly dense but not sparse either. Some but very few berries on each one. They appear to be healthy - just smaller bushes.
My question is this: I know they are slow growers but they haven't put on even one inch of growth since we planted them. (I measured at time of planting) They are the same exact height. What do you think is going on?