Even with its lovely clumps of delicate white flowers, spirea is actually one of the easiest shrubs to grow. Spireas can be planted in less-than-perfect soil, they can thrive in sun or shade and they produce masses of blooms every spring with very little attention. Although it isn't required, a good pruning will keep your spirea looking neat and shapely, and will encourage even more blossoms.
Prune spirea in late winter or early spring. Although 6 to 8 inches is usually enough to stimulate new growth and will preserve the spirea’s natural shape, it’s safe to remove up to 30 percent of the bush.
Remove any dead branches or wood that looks weak or diseased. This will provide air circulation, and will allow energy to go to the healthy branches.
Clip off blooms as soon as they fade and turn brown. You can also cut fresh blooms, which make a lovely bouquet. Trim the branches again after the spire has finished blooming for the season.
Watch the shrub throughout the growing season to notice when it blooms. You must prune the spirea immediately after it blooms to control the size of the shrub. This is because spirea blooms each year on new growth. If you do not shape and prune the shrub right after blooming, you risk cutting away future blossoms.
Cut back and shape the shrub by trimming away the branches that just bloomed.
Lay a 2-inch layer of mulch around the roots, if you desire, but spirea does not require this. Mulching spirea roots is more advantageous for controlling weeds and conserving soil moisture than winter protection.
Leave the mulch around the shrub throughout the year.
Prune your spirea immediately after the blooms fade or in the early spring before new growth appears. Spring pruning works better for summer blooming spirea, as it will preserve more of the seasonal bloom. Spring blooming spirea will keep more of their bloom if pruned immediately after flowering.
Cut back any branches that were damaged, killed or became diseased during the winter. Place the cuts down to healthy wood or remove the branch entirely down to the crown of the plant.
Remove up to one-half of the shrub branch volume each year to encourage bushiness and new flowering branches. Follow the natural contours of the shrub as you shear the branches down to the desired length. Work evenly around the shrub as you cut to ensure a symmetrical and professional finished product.
Decide when to plant. These shrubs are flexible and may be planted in either spring or fall.
Determine the planting location. Full sun locations are preferred for maximum blooming. Ideally, soil should be moist and well-drained but the spirea will tolerate sandy soil or heavy clay.
Dig the planting hole to the same depth as the root ball and approximately 2 to 3 times as wide.
Remove the spirea from its container and position in the planting hole. Add a small portion of the original soil to the planting hole to secure the plant. Fill the planting hole with water and allow to be absorbed. Backfill the remaining soil and water again thoroughly.
Spread a 2 to 3 inch layer of mulch around the base of the shrub and cover the entire planting area. It is best to maintain that level of mulch throughout the year.