To cut or not to cut? That is the perennial question—pardon the pun—when it comes to cutting back plants in fall. With perennials, there is no one perfect time to cut back plants as a group. Some perennial plants should be pruned in fall, while others benefit from waiting until spring. This guide will help take the guess work out of autumn clean-up and provide insight into why you should prune the perennials on this list in fall.
A few simple rules of thumb will help you make decisions regarding fall pruning. Many plants provide benefits over the winter months and can be left in place until spring. Coneflowers, coreopsis, and liatris, for example, provide food for winter birds in the form of seeds. Ornamental grasses also provide food and shelter to birds, as well as height and texture to the winter garden. Plants with interesting seedheads or pods, such as baptisia, also add interest during winter. You also want to wait until spring to cut back plants with evergreen or semi-evergreen foliage, such as hellebores and heuchera.
On the other hand, some plants look unsightly during the winter months and detract from the overall garden aesthetic. These can be cut back after the first few frosts of autumn. Also prune any plants showing signs of disease or insect infestation. Removing infected foliage will help reduce pest outbreaks the following season. Dispose of infected cuttings in the trash rather than the compost pile. A little fall clean up will keep the garden looking good through the winter and help manage pest problems.
Taking time to selectively prune perennials in fall not only helps manage pests, but also frees up time during the busy spring season. Focus on plants that do not contribute to the winter landscape, while leaving those that provide winter interest or resources for birds and other wildlife.
Beebalm
- Botanical Name: Monarda spp.
- Sun Exposure: Full sun to part shade
- Soil Type: Medium to moist, rich
- Soil pH: Slightly acidic to neutral (6.0-7.2)
- USDA Hardiness Zones: 4 to 9
Beebalm is a wonderful native plant for the garden with stunning red, purple, or pink blooms that hummingbirds adore. The foliage of beebalm plants is susceptible to powdery mildew. Cut back the leaves and stems in fall and dispose of cutting in the trash, not the compost pile. Spacing plants further apart to encourage good air circulation and keeping the foliage dry when watering can further help combat this disease.
Hosta
- Botanical Name: Hosta spp.
- Sun Exposure: Part to full shade
- Soil Type: Moist, well-draining, rich
- Soil pH: Slightly acidic to Neutral (6.5-7.5)
- USDA Hardiness Zones: 4 to 9
Hostas are well known for their showy foliage—and their propensity to attract slugs and snails. The eggs of these critters overwinter on withered hosta leaves and other debris. To manage slug populations, cut back hosta foliage to ground level as soon as frost kills it back. Remove the cut foliage and any other debris from around the base of plants.
Iris
- Botanical Name: Iris spp.
- Sun Exposure: Full sun to part shade
- Soil Type: Medium to moist, well-draining, rich
- Soil pH: Slightly acidic to Neutral (6.5-7.5)
- USDA Hardiness Zones: 3 to 10
In addition to a spectacular floral display, iris plants produce gorgeous sword-like foliage. Unfortunately, iris foliage is susceptible to several diseases as well as an insect called the iris borer. All species of iris can be infected. To manage disease, remove infected leaves as soon as you notice them. After the first few fall frosts, cut all foliage back as close to the rhizome as possible. Fall clean-up helps control iris borer as well as foliar diseases.
Yarrow
- Botanical Name: Achillea spp. and cvs.
- Sun Exposure: Full sun
- Soil Type: Dry to medium, well-draining, lean
- Soil pH: Acidic (5.5-6.8)
- USDA Hardiness Zones: 3 to 9
The colorful floral heads of yarrow are a favorite of native bees and butterflies, but they become rather unsightly during the winter months. Keep the garden looking good by cutting back flower stalks in autumn, taking care not to cut the foliage. Yarrow may develop new basal leaves in fall and initiates growth in early spring. Fall clean up allows light to reach this developing foliage.
Garden Phlox
- Botanical Name: Phlox paniculata
- Sun Exposure: Full sun to part shade
- Soil Type: Medium moisture, well-draining, average fertility
- Soil pH: Acidic to alkaline (6.0-8.0)
- USDA Hardiness Zones: 4 to 8
Garden phlox is one of our showier native plants, but it can be challenging to grow. Plants require good drainage to prevent root rot, and the foliage is susceptible to powdery mildew. Cut plants to the ground following a killing frost in autumn to reduce the incidence of powdery mildew the following season. Dispose of cutting in the garbage.
Shasta Daisy
- Botanical Name: Leucanthemum × superbum
- Sun Exposure: Full sun to part shade
- Soil Type: Medium moisture, well-draining, average fertility
- Soil pH: Acidic to neutral (5.5-7.0)
- USDA Hardiness Zones: 5 to 9
Shasta Daisies grow new basal leaves late in the season. Removing spent flower heads helps direct plant energy to this leaf growth rather than seed production. Prune out flower stalks as the flowers fade. Avoid disturbing the basal leaves by cutting stems 2 to 3 inches above the soil line.
Peony
- Botanical Name: Paeonia spp. and hybrids
- Sun Exposure: Full sun
- Soil Type: Medium moisture, well-draining, rich
- Soil pH: Slightly acidic to neutral (6.5-7.0)
- USDA Hardiness Zones: 3 to 8
A few well-timed cuts will keep peony plants healthy and productive for years to come. Start by deadheading flowers after they fade to direct plant energy to next year’s growth and blooms. Then, cut plants to the ground after a killing frost in fall. Autumn pruning helps manage foliar diseases and beautifies the landscape, as peony foliage tends to turn black and unattractive in winter.
Daylily
- Botanical Name: Hemerocallis spp.
- Sun Exposure: Full to part sun
- Soil Type: Medium to moist, well-draining, rich
- Soil pH: Slightly Acidic (6.0-6.5)
- USDA Hardiness Zones: 4 to 9
Daylily foliage dies back to the ground in fall after a killing frost. The foliage doesn’t add visual interest to the winter garden and can, on occasion, harbor foliar diseases. Removing dead foliage in fall prepares plants for the next growing season and reduces remaining tasks for spring, which is a busy time in the garden. After pruning, mulch plants to provide extra winter protection.
Columbine
- Botanical Name: Aquilegia spp.
- Sun Exposure: Full sun to part shade
- Soil Type: Medium moisture, well-draining, average fertility
- Soil pH: Slightly Acidic to Neutral (6.5-7.5)
- USDA Hardiness Zones: 3 to 9
Columbine blooms mid-spring and, in very hot climates, may die back during summer. The plant is host to an insect called the leaf miner which tunnels through foliage. Cut back plants in fall, or earlier if the plant dies back from heat, to reduce leaf miner populations. Columbine reseeds, so remember to scatter any remaining seeds when cutting back plants.
Catmint
- Botanical Name: Nepeta spp. and hybrids
- Sun Exposure: Full sun
- Soil Type: Dry to medium, well-draining, average
- Soil pH: Acidic to alkaline (6.0-8.0)
- USDA Hardiness Zones: 4 to 8
Catmint foliage turns gray in winter, adding nothing of interest to the garden. You can clean up plants in fall and prep them for spring by cutting them back to about 4 to 6 inches above ground level. Another great time to prune catmint is in early summer after the initial spring bloom. Often called the Chelsea Chop, this trim tidies up plants and encourages a second flush of blooms.