Should asters be trimmed back in the fall?
these plants are amazingly hardy through most kinds of weather. We have about ten of them. I chop them down to the ground in the fall and their new growth starts almost immediately and then halts for the winter. It is slow in the spring and then speeds up in the summer. By September and October I have a literal hedge of color that’s about three feet high. Asters will spread via root ‘invasion’ which then sends up new shoots. Unless you want it as a tall groundcover, you will also need to dig up the outlying root systems when you cut the plants down in the fall. Because the roots are not deep around the edges, this is pretty easy. You can use a hand tool or a shovel. Once your plants are about two years old (two years in the ground) you will find them starting to spread and you will want to control that by controlling the root extensions once a year.
