Shorten your spring to-do list by cleaning up, ammending your soil, and tending to your perennials before winter is in full swing.
Stop Fertilizing
If you haven't already, it's time to stop fertilizing your perennial garden beds. Fertilizing this late in the season encourages the plant to prioritize new growth that will simply die off when the cold temperatures hit. By foregoing fertilizer, the plant can go into dormancy and prepare itself for winter.
Since compost is considered a soil conditioner, not a fertilizer, it is safe to apply a layer of compost now. Adding compost in the fall gives it ample time to break down and incorporate into the soil before springtime.
One Final Weeding
Consider going through and weeding one more time before the ground is frozen. Removing weeds with seeds now will lead to fewer weeds to deal with in the spring.
What to Cut Back
The list of plants that absolutely must be cut back in the autumn is limited. However, a few we'd recommend cutting to 2-3 inches above the ground are: bee balm, phlox, peonies, hostas, and bearded irises. These are prone to diseases such as powdery mildew and are notorious for harboring harmful insects over the winter.
Plants that can be cut back in the winter (optional):
- Artemisia
- Bearded iris
- Bee balm
- Campanula
- Catmint
- Clematis
- Columbine
- Coreopsis
- Delphinium
- Daylily
- Salvia
- Shasta Daisy
- Sunflower
- Veronica
- Yarrow
Additionally, any plants that are diseased or infected should be cut back without hesitation and affected foliage should be discarded.
Leave Some Winter Interest
Leaving the majority of native perennials and tall grasses standing provides winter interest (something to look at besides a barren, snow-covered landscape). Plus, the seedheads of flowers like coneflowers provide a natural source of food for birds.
Plants to leave standing:
- Ornamental grass
- Agastache
- Coneflower
- Rudbeckia
- Native sedum
- Joe Pye weed
- Hellebore
- Heuchera
- Garden mums
Consider Adding a Layer of Mulch
The purpose of a winter mulch is to keep the soil temperature even and prevent root damage and heaving due to the soil expanding and contracting in flutuating temperatures. Once the ground is frozen, a layer of mulch around newly planted perennials is a good idea.
Well-established plants will get plenty of insulation from plentiful snow cover and will not require an extra layer of mulch.
Traditional mulch works perfectly well, but shredded leaves, pine needles, and straw are also excellent options that will add nutrients to the soil for easy planting next spring.