Blue shadow fothergilla!

Burning bushes are invasive in many states--you don't tell where you are. Also forsythia (your 'Lynwood Gold') have only a very brief period of interest with nothing whatsoever to recommend them once bloom is over. The fothergilla suggestion is great as long as your soil is not alkaline. But why use 6 of the same shrub? Take a look at Physocarpus 'Lemon Candy' for great chartreuse foliage. Or Spirea 'Ogon' also chartreuse, but quite different.

nothing really stops growing at some magical height...

its all about how much they grow in a given year ... and how many years later it is .. e.g. if it grows a foot per year.. and presuming you start small.. in 10 years.. it will be about ten feet tall ...

your only alternative.. it to use something like REJUVENATION PRUNING OF SHRUBS.... to keep it the size you want ...

bushes is a common descriptive term... for searching purposes.. you will get further searching for FLOWERING SHRUBS ...

and i would also note.. anything called 'fast growing' .... will most likely. get much bigger .. much faster.. than you probably want ...

also.. keep in mind.. that flowers attract bees.. and that might not be what you want.. at your front door ..;

i dont think you mention where you are... so its hard to be overly specific with suggestions ...

and finally ... it seems.. reading between the lines.. you want instant gratification .... in the sense that you want the space filled this summer... whenever i tried this system.. i usually ended up with a monster that had to be removed.... too soon ...

good luck

ken

In zone 6 wouldn't you like a few evergreens for the winter interest?

Evergreens are so much nicer for foundation plants.
Where are you?
Mike