If you prune them now you will lose the bloom for this year. I would wait until they are done blooming (unless you don't mind losing the bloom) and then prune them. I prune mine to about 6 inches (since they are often broken by snow from the roof dumping on them) and they will regrow quickly. If you cut them higher the shape and branching is pretty awful looking IMO.

I should clarify, they are not "blooming" as I stated in my first post, but "budding", do you offer the same advice?

they can literally be cut to the ground .. hey wait a minute.. care to fully ID which one we are talking about???

in general ... you can cut the whole thing to the ground.. AFTER flowering .. or now if you dont care about the flowers ... and it will be 2 foot tall by fall ...

or you can cut all the largest trunks.. as close to the ground as you can get .. and use rejuvenation pruning to to keep it in a good form... hit the link.. and find a link that makes the most sense to you ...

the one thing you do NOT want to do.. is cut branches at height.. or shear it.. because the explosive growth at height.. will make it all fall down next year.. and you will have a bigger mess ...

ken

Here is a link that might be useful: link

If it's budding or starting to push leaves, prune now. My spirea are summer blooming and I prune them right down. Mine grow to their full height of 3-4' each summer. I don't bother to prune them when they don't look ratty and they end up looking the same by the time the end of May rolls around.