In the fall after bloom.
Some gardeners do cut back the leaves in fall to prevent mold and disease.
In order to tell if a Spirea shrub is dead, the branches must be thoroughly looked at. If they are brown, brittle, and fall right out when touched, then the bush is probably dead.
Spirea can be trimmed lightly or severely depending on what you are trying to accomplish. If you just want to clean up the spent flower blooms, just cut them off with pruners. Depending on your climate and when you do this, you may get additional blooms the same season.If you want to control the size of the plant to keep it smaller, you can cut it down to any length you desire. This is best done in the early spring or late winter before new growth comes out. If you wait later, you will be risking losing that season's blooms. Spirea are very very durable and they will take most anything. I have sometimes cut it back from 4' to 1'. Shape it to mimic its natural shape, mounded. The general rule for pruning trees and shrubs is never remove more than a third of the plant. But spirea do not read the rule books and you can break this one!As far as I know, the above applies to all types of spirea.
Spirea X ended in 1993.
Spirea X was created in 1990.
Cut off the old flower stems leave the leaves.
Cut off the old flowers the foliage will die back naturally in the Autumn.
After blooming is done, you can cut back the flower stalks, but don't cut back the leaves until you are ready to separate and transplant irises in the fall. When you take them out to replant, cut the leaves down into about a 4 to 5 inch fan shape.
I am no gardening expert, but I love plants, flowers, dirt and watching the garden grow. I currently have 11 spirea planted in various locations in gardens around my home. Anthony Waterer, Neon Flash, Princess Spirea and Bridal Wreath Spirea are what I chose to plant and all are thriving. 7 Spirea receive morning sun ,( by 2 p.m. are completely shaded) 1 receives partial sun, and 3 receive hot afternoon sun (morning shade until 1:30pm). Every year I add compost and new mulch around these plants. In the Fall or early Spring I cut back ( prune hard) the Anthony Waterer and Neon Flash Spirea, leaving 3 to 4 inches. Every Spring they grow with such vigorous growth. If your spirea are dying, I would try moving them to another location in the garden. Then perhaps add new soil mixed with compost and top with a couple inches of mulch. Sometimes gardening is learning by trial and error, not being afraid to move plants around the garden until you find a place they thrive. Sometimes we need to cut away a good portion of the plant to trigger new growth. I also find gardening books from the library very helpful. Many of my neighbours love to garden, so sometimes I ask them about a particular plant, because they probably have experienced similar problems and may have needed solutions. I hope some of this information will be helpful. Ever Learning, Zone 5
Wait until the flower spike dies back then cut it just above the leaf.
Cut a wedge in the direction you wish the tree to fall. Make consecutive cuts from both sides and a final cut from the back.