Avoid Cutting Back These 10 Perennials This Fall
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Fall is typically the season for cutting back herbaceous perennials and woody shrubs. While the fall season is ideal for pruning and cutting back a wide variety of plants, there are a handful of perennials that you should avoid cutting back this fall. In this article, we’ll review which plants you should avoid and why!
(Featured Image: Perennial Flower Hedge by J. Miller)
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Why Is Fall When Many People Cut Back Perennials?
Fall is generally considered a great time to cut back a wide variety of perennial flowers and shrubs, and in general take care of a lot of yard clean-up. The primary reasons fall is a popular season for pruning includes:
Plant Dormancy
In the fall, many perennial plants start to enter a state of dormancy as temperatures drop and daylight decreases. During dormancy, the plant’s metabolic activity slows down, and it becomes less susceptible to stress caused by pruning. This reduced stress makes it an ideal time for cutting back without causing undue harm to the plant.
Disease and Pest Management
Cutting back perennials in the fall can help remove diseased or pest-infested foliage, reducing the chances of these issues overwintering and reemerging in the spring. It’s essential to dispose of any diseased plant material properly to prevent the spread of diseases.
Aesthetic Cleanup
Fall cleanup of dead or decaying foliage and spent flower heads can improve the overall appearance of your garden. Removing unsightly plant material can also prevent the garden from becoming a breeding ground for pests and diseases.
Preparation for Winter
Trimming back certain perennials in the fall can help protect the plant from winter damage. For example, cutting back ornamental grasses in late winter or early spring can expose the crown to hard frosts if not timed correctly, potentially causing harm. Leaving them intact through the fall helps insulate the base of the grass.
Encouraging New Growth
Pruning perennials in the fall can stimulate new growth in the spring. This can be advantageous for plants that benefit from rejuvenation or need to be shaped for aesthetic reasons. Cutting back in the fall allows the plant to focus its energy on root development and preparing for the winter.
Wildlife and Habitat
Leaving certain perennials uncut in the fall can provide habitat and food for wildlife, such as birds that feed on seed heads or beneficial insects that overwinter in plant material. This can contribute to a more biodiverse and ecologically friendly garden.
While fall is a suitable time for cutting back many perennials, it’s important to note that the timing may vary depending on the specific plant, your climate zone, and local weather conditions. Some perennials are best pruned in late fall, while others may benefit from pruning in early spring. The list below includes many common perennials that are not good candidates for fall pruning.
Tall Perennial Flowers
10 Perennials You Should Avoid Cutting Back This Fall
1. Ornamental Grasses
Ornamental grasses, such as Miscanthus or Pennisetum, have attractive seed heads that can add interest to the winter landscape. These seed heads can catch and glisten with frost or provide a unique textural element when covered in snow. Additionally, they offer protection to overwintering insects and provide habitat for birds that may feed on the seeds. Trimming them back in late winter or early spring before new growth emerges ensures a tidy appearance without sacrificing their winter appeal.
Karl Foerster Grass is a popular choice for gardeners that want to add fall and winter interest to their yards. Each fall, decorative tassles grow from the tops of the tall grass. These remain upright and collect snow and ice in the winter months, adding texture and height to any landscape.
2. Sedum (Stonecrop)
Sedum is a succulent perennial that often retains its foliage well into the winter, offering visual interest with its unique foliage and seed heads. Leaving the spent flower heads and foliage intact during the fall can provide a protective layer for the plant against harsh winter conditions. Pruning them in late winter or early spring helps remove any dead or damaged growth while allowing new shoots to emerge.
Autumn Joy Sedum (pictured right) is a common stonecrop variety that is chosen for its beautiful fall blooms and upright foliage. This plant is hardy for northern winters, and adds a lot of color to fall landscapes.
3. Echinacea (Coneflower)
Coneflowers produce distinctive seed heads that can be left standing in the fall and winter. These seed heads not only add visual interest but also provide a food source for birds. Cutting purple coneflowers back in early spring allows for a clean start for new growth while benefiting wildlife during the colder months.
Coneflowers are native to the midwest and many other regions of the United States. Not only are these flowers easy to grow and maintain, but they come in a wide variety of colors that can stand out in a crowd. The Sombrero Salsa Red Coneflower boasts a bright red bloom among a blanket of deep green foliage.
4. Rudbeckia (Black-Eyed Susan)
Like Echinacea, Black-Eyed Susans produce seed heads that can remain in the garden throughout the fall and winter. These seed heads offer sustenance to birds and add a touch of structure to the winter garden. Pruning them back in early spring helps rejuvenate the plant for the upcoming growing season.
The Goldstrum variety of Black-eyed Susans is a popular choice for its dainty, but abundant, flower heads. This native flower is a prolific spreader and is great for meadow or cottage gardens. This type of black-eyed Susan also makes a beautiful cut flower!
5. Milkweed (Asclepias)
Milkweed is essential for the survival of monarch butterflies, as it serves as a host plant for their larvae. Leaving the dried seed pods in place during the fall and winter supports both monarchs and other beneficial insects. Trimming them back in early spring ensures healthy regrowth.
There are several varieties of native milkweed that are all beneficial for butterflies, especially the endangered Monarch butterfly. Selecting a variety of milkweed plants, like this variety pack by Sereniseed, can ensure your garden has good diversity and can host and feed a large number of butterflies.
6. Lavender
Lavender plants benefit from winter protection for their base and lower stems. Leaving some of the green growth intact during the fall can help shield the plant from winter winds and cold temperatures. Light pruning in the spring, just before new growth starts, maintains the plant’s shape and encourages vigorous growth.
Lavender is typically a very hardy plant that can thrive in difficult conditions. The Phenomenal Lavender plant is a special cultivar that is specifically bred for its tolerance to less-than-ideal growing conditions.
7. Peonies
While it’s common to remove the brown and decaying foliage of peonies in the fall, it’s essential to avoid cutting back the green stems too early. The green stems continue to photosynthesize and provide energy for the peony’s growth in the next season. Waiting until late fall or early winter to trim them back allows the plant to maximize energy storage.
Beautiful yellow peonies can be a unique addition to any garden hedge. The Bartzella Itoh peony features large, yellow blooms that truly stand out in a crowd!
8. Sage (Salvia)
Salvias, especially perennial varieties, can benefit from having some of their old stems left in place during the winter. These stems provide some insulation for the crown of the plant, protecting it from freezing temperatures. Light pruning in late winter or early spring helps maintain compact and healthy plants.
Russian Sage is an immensely popular perennial flower that blooms for many weeks in late summer to early fall. This is a hardy perennial that can stand up well to harsh winters and hot, dry summers.
9. Heuchera (Coral Bells)
Heuchera has semi-evergreen to evergreen foliage, which means it can retain its attractive leaves throughout the winter. While some old leaves may turn brown, many stay green. Pruning away any damaged or unsightly leaves in the spring keeps the plant looking its best as new growth emerges.
Palace Purple Heuchera are a great alternative to hostas as they are native to many regions of the US. These are often planted as ground cover due to the fact that they grow low to the ground and can fill in larger areas rather quickly.
10. Hellebores (Lenten Roses)
Hellebores are prized for their evergreen foliage and early spring blooms. They can be left largely untouched during the fall and winter months to maintain their appearance and protect their buds. Trimming away any damaged leaves or old flower stalks in the spring helps the plant look its best for the new growing season.
In summary, these perennials are best left unpruned or minimally pruned in the fall to preserve their visual appeal, provide winter interest, and support wildlife. Pruning them in late winter or early spring, before new growth emerges, is typically the best time to cut these perennials back. This gives the plants ample time to form buds for the following year.
How To Properly Cut Back Perennials In The Spring
Pruning perennials in the spring is a key part of maintaining a healthy and vibrant garden. Here’s a step-by-step guide on how to properly cut back perennials in the spring:
Tools You’ll Need:
- Pruning shears or garden scissors
- Hedge trimmers for woody perennials (we LOVE this hedge trimming set by Ryobi!!)
- Gloves (to protect your hands)
- Wheelbarrow or compost bin (for collecting and disposing of plant material)
10 Steps to Properly Cut Back Perennials in the Spring:
- Wait for the Right Time: Spring is the ideal time to cut back many perennials because it allows you to remove any winter-damaged or dead growth while encouraging new growth to emerge. Wait until the threat of frost has passed, and you start to see signs of new growth at the base of the plant.
- Assess the Plant: Before you begin pruning, closely inspect the plant to identify any dead, diseased, or damaged growth. Also, check for signs of new growth emerging from the base of the plant.
- Wear Gloves: Always wear gardening gloves to protect your hands from thorns, splinters, or any potential skin irritants.
- Prune Dead and Damaged Growth:
- Start by cutting away any dead or winter-damaged foliage and stems. Make a clean cut just above a healthy leaf or bud node using sharp pruning shears.
- Remove any stems that show signs of disease or pest damage. Dispose of the removed plant material in a wheelbarrow or compost bin, ensuring that diseased material goes in the trash and not the compost.
- Prune foliage that makes the plant shape look awkward or unbalanced.
- Cut Back Spent Flower Stalks:
- Remove any spent flower stalks to encourage new blooms. Cut them back to a healthy set of leaves or flower bud.
- For plants like Echinacea and Rudbeckia, you may want to leave some of the seed heads for winter interest or wildlife habitat.
- Prune for Shape and Size:
- If the perennial has become leggy, floppy, or overgrown during the winter, you can prune it back to achieve a more compact and balanced shape. Make cuts just above a leaf node or healthy set of leaves.
- This is particularly useful for perennials like garden phlox (phlox paniculata), Joe Pye Weed, and Coreopsis (common name tickseed)..
- Use this as a chance to shape the overall look of your plant for the following season.
- Cut Back Woody Perennials:
- For woody perennials, such as lavender or Russian sage, use a pruning saw or loppers to make the cuts. Remove any dead or overgrown wood, and shape the plant as desired.
- Make clean cuts close to the base of the plant.
- Leave Some Stems for Winter Interest or Wildlife:
- If desired, you can leave some stems and foliage on certain perennials for winter interest, bird habitat, or to protect the plant from harsh spring conditions.
- For example, some ornamental grasses and native plants are often left uncut in the spring.
- Clean Up and Dispose:
- Collect all the pruned plant material and dispose of it properly. Compost healthy plant material or discard it in the trash if it’s diseased or pest-infested.
- Rake up any debris and fallen leaves around the base of the plants to reduce overwintering pests and diseases.
- Mulch and Fertilize:
- After pruning, consider adding a layer of mulch to help retain soil moisture and suppress weeds.
- Apply a balanced fertilizer according to the specific needs of your perennials and the recommendations for your region.
Always research the particular needs of your plants and adapt your pruning routine accordingly to maintain their health and vitality. Pruning in the spring is an excellent way to rejuvenate your perennials and prepare them for a season of growth and bloom.
Get Your Yard Ready For The Fall Season
As a general rule, fall has classically been a time for cleaning up the yard from plant debris and dead leaves in preparation for the winter season. Recently, however, there has been a push to avoid some of fall clean up routine until spring, as much of the old foliage and flower stems are actually very beneficial to local wildlife and insects which can help boost your garden in the spring.
To learn more about what to do with your garden during the fall season, check out these related articles:
