Cutting back perennials can help maintain garden health and appearance, but you might choose to leave certain plants untouched to enhance winter interest and provide habitat for wildlife.
Cutting back perennials in the fall can be beneficial, but whether or not to do so depends on the type of plant and your preferences for garden aesthetics and plant health. Here are the key considerations:
Benefits of Cutting Back Perennials in Fall
Perennials to cut back in the Fall
When to Wait Until Spring
How to Cut Back
Benefits of Cutting Back Perennials in Fall
- Disease Prevention: Cutting back dead or dying foliage can prevent the spread of diseases or pests that might overwinter in the plant debris. This is especially important for plants prone to fungal infections, like peonies or irises.
- Tidier Garden: Removing spent flowers and foliage in the fall keeps the garden looking clean and well-maintained through the winter months.
- Encourages Healthy Growth: Pruning perennials helps channel the plant’s energy toward root development over the winter, promoting stronger growth in the spring.
Perennials to cut back in the Fall
- Anything with powdery mildew or other obvious disease. Dispose of all diseased foliage and blooms by bagging and throwing in trash. Never compost diseased plant materials.
- Blazing Star (Liatris) - looks tidier if cut back but wait till it naturally dies back before cutting
- Catmint - cutting back removes an unkempt look. Prune back to about 4-6 inches above soil.
- Daylilies - cut back after first frost to keep garden looking tidy. Cutting back too soon can interfere with this plant's photosynthesis and affect their overall health.
- Garden Phlox - cut back to address powdery mildew. Do not put diseased foliage in the compost pile.
- Hostas - slugs lay eggs in their foliage during Autumn - so cut this one back after they have died naturally.
- Iris and other bulbs - cut dead leaves off just above the crown, and the green leaves 4-6 inches above the soil. Wait till after first Fall frost to give plants as much time as possible to store food.
- Lavender - this plant produces leaves and blooms only on old wood, so cut plant just above the woody sections (never in to the woody section). Do this 6 weeks before first frost if possible to help lavender be less vulnerable in winter.
- Peony - cut back to a few inches above ground.
- Gaillardia daisy (Blanket flowers) - deadhead spent blooms and cut back the plants before winter to keep them healthy for next year.
- Salvia - cutting back in the Fall means the possibility of two blooms next year instead of one, and keeps them from developing woody stems.
When to Wait Until Spring
- Winter Interest: Some perennials, like ornamental grasses, sedums, and coneflowers, provide visual interest and structure to the winter garden. Their seed heads can also serve as food for birds.
- Protection for Plants: Leaving the foliage on certain plants can provide a layer of insulation during the cold months.
- Pollinators and Wildlife: Some insects, including pollinators, overwinter in plant stems, so leaving them intact can support local ecosystems.
How to Cut Back
- For perennials that need cutting back, prune the stems down to a few inches above the ground after the first frost when the plants have naturally started to die back. Be sure to remove any diseased or damaged foliage and dispose of in trash.