It's common practice to cut the entire perennial bed down to about 6" in late fall to remove any old debris that will be in the way next season. This is also a good time to pull out any dead annuals from the border so there is no question in the spring whether a dead looking clump is really dead or is actually a valuable perennial, not yet awake. Most perennials will show signs of life at the crown early in the spring, and with the annual tops gone the fall before, spring cleanup can be delayed quite a while. No plants need to be lost to an overzealous worker! A light application of fertilizer can be made anytime from late fall to early summer on established beds to maintain the health of the bed.
We are often asked about what, when, and how to trim plants for over wintering. Eventually youíll want to remove the plantís spent foliage, as most will be wintering at or below the soil line. (New growth is coming next spring, donít worry!) Cutting the plant back to 4-6" high is a good rule of thumb. You can use almost anything from scissors, hand pruners, grass shears, to hedge shears (our personal favorite). Now is also a good time to pull out any annuals, as they wonít be coming back like your perennials will. You donít have to cut back everything in the fall. Here are some guidelines we like to use.