Overgrown Beauty Bush (Kolkwitzia) pruned hard, now what?
We moved into our new home in fall 2008. There is a fairly steep hill down to the lawn from the road, and it was a gigantic tangle of sumac, multiflora rose, and several very overgrown shrubs. We've cut out the invasive stuff and are trying to renovate the shrubs. (An unusual lilac, some forsythia, some quince, a couple spirea and wigela, and these 2 Beauty Bushes.)
The Beauty Bushes were probably 20' tall and wide. The branches/shoots -some of them 6-7" diameter- made a mass perhaps 36" across at the base. Last spring we completely cut them back to the ground. Over the summer, they sprouted new shoots. The problem is, these new shoots -hundreds of them per shrub!- are filling the entire 36" diameter footprint of the old shrub.
It's a problem because the walkway down from the road will be blocked by them if they get to be 20' wide again. I was really hoping that we could keep them a little bit smaller!
I keep reading about people's Beauty Bush that top out at 6'-8' high and wide. Is that possible with my shrubs?
Can I prune out most of the outer shoots, especially the prostrate ones, for a more upright, vase-shaped plant? Ideally I would like the base of the plant to only be 12" diameter not 36". Is that possible at this point if I keep cutting down the outer shoots?
It seems like it's just way too dense right now, with all those hundreds of shoots, to be a healthy plant.... but I am not sure how to go about pruning it properly.
Any help appreciated!