Hydrangea paniculata types Some can get pretty big. I have three limelights on the west side of our house and we haven't pruned them in the 3 1/2 years we've lived here. They have reached 7-8 ft tall. Pretty sure they were planted the year before we moved in. Hydrangeashydrangeas.com has pictures of several varieties but their pinky winky picture isn't loading for me. I usually say shrub but may describe a plant as bushy (even if it isn't a shrub). Butterfly bush is an exemption though...hm though here butterfly bushes are more like shrubby perennials, I mean bushy perennials... Here is a link that might be useful: Pictures of hydrangea paniculata varieties

the flower is a hypercium, the multicolored leaves are golden eunymous which I think looks cheap.

Harpua, yes, it has generally been wet, soil moisture is returning to normal (after a two year drought in some areas of the Northeast), but if I recall correctly, yours went into the ground shortly before we had a few days in the mid 90's. Wonder if that might have given them a stressful start (transplanting is stressful enough). Personally, I think they will eventually all fill in as long as you maintain soil moisture over the course of next few years (until they get established). I have a few of these in NJ/Zone 7 as a privacy hedge as well. They really are quite trouble free and normally are quite vigorous. If you continue to experience problems, there may be some other undedicated issues (drainage problems, etc.)

mxk3 I'm not certain at the moment, I'm just considering it because I remember how tasty their berries were way back when I was little and especially because I don't remember seeing so many black raspberry shrubs as I have this year; in fact for the last few years I don't recall seeing any canes. And it's not just near my house either; along the street parallel to ours (also part of our neighborhood) there's even larger groups of them that appear to be growing faster than the ones by my yard. Right now I'm thinking of just placing one cut cane of a shrub in a deepish pot and then see how it grows over the next couple of months. If it does end up growing like crazy and spreading too fast for me to manage, I'll know not to actually plant them in the yard.