I'm having the same trouble with my clones.....the mother is big, bushy and beautiful....and budding, but the three clones are all stunted. I've transplanted them and they all have great root structure, but every one of them are no more than three inches tall.
One of the clones I'm trying to flower, thinking maybe that will start it growing outward.
The other two I have under vegetation, but they are not growing outward like the parent plant has.

I'm using Flor in the veg stage(18-6), and 1000 watt HPS for flowering.(12-12)

I'm also looking to solve this problem. Any advise??