Pruning Spirea is probably one of the EASIEST things to do. In fact you cant really go wrong. Its recommended that you prune spirea every other year so it doesnt grow wildly out of control.
You can cut back the overgrown branches to shape your plant, or you can do what is referred to as rejuvenation pruning to promote new growth and better flowering. First, cut out all the dead stuff. Then cut 1/3 of the branches straight to the ground where you would like fresh growth. Give it some room to breath, keep it watered, then let it do its magic.
Theres some confusion online as to WHEN spirea can be pruned to keep its flowers. There are different types and each bloom at a different time, so a good rule of thumb is to prune right after its finished blooming. In the case of these sad shrubs I picked up, I had a feeling it didn’t matter how much I hack off and when. So I did something kind of crazy.
I scored two Bridal Wreath Spirea shrubs from a neighbor. Being old bushes, getting them to budge was incredibly difficult. One shrub had grown completely sideways, I had cut the top off to fit it in my car. The other fell apart in my hands. Im not exactly proud to admit that job was a mess. What I put these poor plants through.
Luckily, Spirea is one tough shrub. After serious research, I learned that you can basically hack these things to the ground and they’ll come back even stronger… I wasnt exactly sure what was going to happen, but heck, I had nothing to lose. So that’s what I did.
Pruning Spirea:
The large sideways grown spirea shrub after transplant on 8-23-10
The one that fell apart. 8-23-10
UPDATE! 9-23-10
It WORKED! Just one month later, and look at all the new growth.
Here’s, the large sideways grown spirea shrub after just one month
The one that fell apart.. and now i have four!
If you have a healthy spirea in your landscape, you wouldn’t do something quite so drastic, but your spirea does need pruning. Older plants can get out of hand quickly, so its a good idea to stay on top of pruning spirea.
UPDATE 5-27-2013
Well, it took 3 years, but these spireas finally DID flower again, and they are gorgeous! By now theyre over 3 feet tall and covered with beautiful flowers. Id say the experiment was a success!