I also subscribe to their e-mail list and I receive even more tips that way. I just had to share this good advice for pruning spirea. I like mine to be natural but you may prefer a rounded bush. There are directions for both ways here.
Here is my Little Princess Spirea that is peeking out from behind the Hosta in my front yard (it is the lime green shrub). This particular variety will be covered with hot pink flowers in a few days and will bloom all summer if I deadhead it. Follow the link below for pruning directions.