If I get busy and shear the spent blooms off immediately after bloom, I'll often get a rebloom of lesser quantity in late summer or early fall. My plants have finished blooming, for the most part, although the stem, scanned here to show the typical simple, double toothed leaf shape and alternate leaf spacing on the stem, has new flowers. This stem is young, as evidenced by the green color. Old stems are a dark, reddish brown. New leaf growth is also somewhat reddish, which adds interest in early spring.
Stems are slender and twiggy, making the texture fine in all seasons.
Since flowering is on new wood, you can shear these plants back hard in late winter or very early spring, if you like. Sometimes, I simply take my electric hedge trimmer to them as it is faster than clipping them over by hand. I should have put a dime or penny with this for scale when I scanned it, since this image is quite a bit larger than real life. Spirea flowers are either white or pink, with some a deep enough pink to be called red. The reverse side of the flower cluster reveals the branching of the individual flower stems.