Autumn is the perfect time to spruce up garden beds with a thick layer of mulch. And while you’re busy cleaning up your garden, you can also tidy up the lines of some of your perennial plants with late-season pruning. However, certain plants do better with fall pruning than others, and if you cut back the wrong plants in autumn, you may accidentally remove flower buds and limit future blooming!
Beyond reduced blooms, when some plants are pruned in fall, they can become more vulnerable to freezing temperatures and frost damage. That’s why if you want your perennials to survive the winter, it’s important to know which plants should and should not be cut back in fall. In this guide, we’ll introduce you to 15 common perennials that should never be cut back in fall… but if your pruning shears are itching to prune plants, we have a full guide on plants that SHOULD be cut back in autumn right here.
Jump to:
- 15 perennials you shouldn’t cut back in fall
- 1. Lilacs (Syringaspp.)
- 2. Rhododendrons (Rhododendron spp.)
- 3. Azaleas (Rhododendron spp.)
- 4. Roses (Rosa spp.)
- 5. Forsythia (Forsythia spp.)
- 6. Old wood hydrangeas (Hydrangea spp.)
- 7. Globe thistle (Echinops bannaticus)
- 8. Russian sage (Perovskia atriplicifolia)
- 9. Coneflower (Echinacea spp.)
- 10. Black-eyed Susan (Rudbeckia hirta)
- 11. Mock orange (Philadelphus coronarius)
- 12. Viburnum (Viburnum spp.)
- 13. Lady’s mantle (Alchemilla mollis)
- 14. Ninebark (Physocarpus spp.)
- 15. Ornamental grasses
- Frequently asked questions
- Summary
15 perennials you shouldn’t cut back in fall
When pruning plants in fall, you’ll want to time your pruning correctly. Fall pruning should generally occur in early to mid-fall, about 4 weeks before your first frost date. Cutting plants back later than that can expose some perennials to winter damage and make them less likely to survive the long winter ahead!
1. Lilacs (Syringaspp.)
| Plant name: | Lilacs |
| Growing zone: | Zones 3 to 8 |
| When to prune: | After flowering in spring to early summer |
| Blooms on old wood? | Yes |
Lilacs are springtime favorites, well known for their fragrant clusters of purple and white flowers and heart-shaped leaves. Easy to grow and versatile, lilacs come in tall and dwarf varieties, and they’re the perfect complement to cottage garden displays. For even more options, easygoing lilacs can also be grown in privacy hedges, and they make showy accent plants, too!
But while lilacs don’t need a lot of attention, if full-sized lilac plants are allowed to grow wild, they can stretch over 30’ tall, and their branches can get scraggly over time. To avoid this, many gardens prune their lilac shrubs annually, but it’s best to prune lilac shrubs immediately after they flower in late spring to early summer. Fall pruning is not recommended with these plants as lilacs bloom on old wood, and a late season pruning can clip away their flower buds and reduce springtime blooming.
2. Rhododendrons (Rhododendron spp.)
| Plant name: | Rhododendrons |
| Growing zone: | Zones 4 to 8 |
| When to prune: | No later than 3 weeks after flowers fade |
| Blooms on old wood? | Yes |
Rhododendrons are favorites in shade gardens, and their evergreen leaves add a subtle hint of color to garden beds even in winter. But most gardeners love rhododendrons for their bright, pinkish-purple, trumpet-shaped flowers, which are almost always coated in bees! Rhododendrons are also staples in gardens with poor or acidic soils, as these tough plants can thrive in adverse conditions where other perennials just won’t take.
In general, rhododendrons are pretty low-maintenance plants that don’t need much pruning. However, if you want to reshape your rhododendron shrubs, don’t do it in the fall! Like lilacs, rhododendrons only bloom on old wood, and they should be pruned no later than 3 weeks after the plant flowers in spring to early summer.
3. Azaleas (Rhododendron spp.)
| Plant name: | Azaleas |
| Growing zone: | Zones 5 to 9 (some varieties are less cold hardy) |
| When to prune: | No later than 3 weeks after flowers fade |
| Blooms on old wood? | Yes |
Azaleas are closely related to rhododendrons, so it’s not surprising that they have very similar care requirements. Like rhododendrons, azaleas only bloom on old wood, and if you prune the plant in autumn, you risk removing all of your flower buds. Instead, these plants should only be pruned immediately after they finish flowering in spring or summer.
If you’re new to working with rhododendrons and azaleas, you’ll note that these plants look quite similar. However, azaleas are often smaller plants with narrower leaves. Many varieties of azaleas are small enough to grow in containers, and you can even find reblooming varieties that will flower throughout summer.
4. Roses (Rosa spp.)
| Plant name: | Roses |
| Growing zone: | Zones 4 to 10 (most varieties) |
| When to prune: | Late winter to early spring (most varieties); After summer flowering for rambling rose varieties |
| Blooms on old wood? | Some varieties |
Roses are the favorite plants of many gardeners, and some gardeners dedicate their entire landscape to rose bushes. Part of the allure of roses is due to their versatility, as you can find roses that climb, as well as highly fragranced cultivars and dwarf beauties that are ideal for container growing. Most roses also produce large and colorful rosehips, which are edible and delicious in teas and jams.
But if you want your rose bushes to grow well, avoid the temptation to prune them in autumn. While you can do a bit of minor pruning on your roses late in the season, significant pruning should be reserved for winter or early spring. Fall pruning can sometimes cause rose bushes to leaf out late in the season, exposing plants to cold damage, while winter pruning is ideal since roses will be dormant at this time of the year.
Tip: While winter pruning is recommended for most types of roses, rambling roses will grow best if they’re pruned in summer, immediately after their flowers fade.
5. Forsythia (Forsythia spp.)
| Plant name: | Forsythia |
| Growing zone: | Zones 4 to 9 |
| When to prune: | After flowering in spring to early summer |
| Blooms on old wood? | Yes |
Like lilacs, forsythia is another flower garden favorite, famed for its brilliant yellow flowers, which are some of the first flowers to bloom in spring. Since forsythia bloom so early in the year, their delicate flowers are magnets for pollinators, which are just emerging from winter hibernation. But if forsythia shrubs aren’t pruned from time to time, they can become unruly and overwhelm small garden spaces.
Since forsythia bushes grow so vigorously, it can be tempting to prune them back late in the year to get a head start on the growing ahead. But like some of the other plants on this list, forsythia bloom on old wood, and fall prunings can damage their developing buds. To avoid this, prune forsythia after the plant’s flowers fade in spring, and never remove more than ⅓ of your forsythia branches in one go.
6. Old wood hydrangeas (Hydrangea spp.)
| Plant name: | Old wood hydrangeas |
| Growing zone: | Zones 3 to 9 (many varieties) |
| When to prune: | After flowering in spring to summer |
| Blooms on old wood? | Yes |
Hydrangeas are confusing plants since some hydrangeas bloom on old wood, and others bloom on new wood. Varieties like panicle and smooth hydrangeas fall into the later category, and they produce flower buds only on new growth. As a result, these cold hardy hydrangeas can be pruned back in fall, although they’ll do better if you cut them back in late winter to early spring.
However, hydrangeas varieties that bloom on old wood are a different story altogether. Bigleaf, oakleaf, and climbing hydrangeas, for instance, only produce flower buds on old growth, and if you prune them in autumn, you can remove all your plant’s buds, and you’ll have no hydrangea flowers the following spring! To avoid this gardening tragedy, be sure to only prune old wood hydrangeas in spring to early summer (no later than July), just after the plants finish flowering.
7. Globe thistle (Echinops bannaticus)
| Plant name: | Globe thistle |
| Growing zone: | Zones 3 to 10 |
| When to prune: | Often doesn’t need pruning but can be cut back in spring |
| Blooms on old wood? | N/A |
Unlike some of the other plants on this list, globe thistle will still grow and flower beautifully even if you cut it back in the fall. However, these plants produce large seed heads that are favorite treats for wild birds in winter. Cutting back globe thistle plants in autumn can remove these seeds and reduce the natural food resources that are available for wildlife.
Aside from their seeds, globe thistle flowers generally stay upright during winter, and they can look very pretty when they’re topped with snow. Some gardeners even grow globe thistle plants just to add winter interest to their gardens, although globe thistles look stunning all year round. During the growing season, globe thistles enliven garden beds with their spiky, globular flowers that come in a brilliant, near-electric blue color… and they make exceptional cut flowers as well!
8. Russian sage (Perovskia atriplicifolia)
| Plant name: | Russian sage |
| Growing zone: | Zones 4 to 9 |
| When to prune: | Spring |
| Blooms on old wood? | N/A |
Russian sage is a favorite in pollinator gardens, where its amethyst-toned blooms make favorite stopping spots for bees and butterflies. In ornamental beds, Russian sage adds an airy quality, and the plant’s silvery-green leaves make garden designs feel brighter and more complex. Not to mention, Russian sage exudes a delicious, menthol-like fragrance, which makes the plant naturally resistant to deer predation.
If you’ve ever grown Russian sage plants, you’re no stranger to the charms of this beautiful ornamental. But it’s important to remember that Russian sage plants often don’t respond well to autumn pruning. Cutting back Russian sage plants in autumn can expose the plants’ delicate crowns to cold damage, so avoid pruning them until spring and keep the plant crowns covered up with a layer of insulating mulch until then!
9. Coneflower (Echinacea spp.)
| Plant name: | Coneflower |
| Growing zone: | Zones 3 to 9 |
| When to prune: | Late winter |
| Blooms on old wood? | N/A |
Pruning coneflowers in autumn isn’t a recipe for disaster, but there are many reasons why you may want to skip it anyway. Like globe thistles, coneflowers produce large seedheads, which provide a protein-packed treat for birds in winter. Overwintering pollinators may also use the dead stems and leaves of coneflower plants for winter protection, and dried coneflowers can add winter interest to your garden beds as well!
On top of all that, coneflower plants readily self sow if you don’t prune away their flowerheads. So if you want to get more free “volunteer” coneflowers for your garden, put away those pruning shears until spring. Once temperatures start to rise, you can prune away the spent stems of coneflower plants and add them to your compost pile, but take care that you don’t damage the plant’s new green leaves and shoots.
10. Black-eyed Susan (Rudbeckia hirta)
| Plant name: | Black-eyed Susan |
| Growing zone: | Zones 3 to 10 |
| When to prune: | Late winter to early spring |
| Blooms on old wood? | N/A |
As with coneflowers, black-eyed Susan provides foraging spots for many wild birds in winter. Finches, chickadees, sparrows, cardinals, and nuthatches all flock to black-eyed Susan flowers when other food sources are scarce, and pollinators will also overwinter in the plant’s dead foliage. What’s more, these plants vigorously self sow and you can get tons more black-eyed Susan plants if you don’t remove their spent flowers!
Instead of pruning your black-eyed Susans in the fall, apply a neat layer of mulch around your plants to insulate their roots. If you want to give your perennials an extra boost, you can also apply a slow-release fertilizer like compost, which will break down over the winter months and enrich your garden soil. When spring arrives, you can clip away the old stems from black-eyed Susan plants, or you can allow them to naturally degrade back into your garden soil… it’s up to you!
11. Mock orange (Philadelphus coronarius)
| Plant name: | Mock orange |
| Growing zone: | Zones 3 to 8 |
| When to prune: | After flowering in spring to early summer |
| Blooms on old wood? | Yes |
Mock oranges are commonly grown in cottage garden displays, but they look right at home in mixed flower beds, too. While these low-maintenance plants produce showy flowers in spring and early summer, mock orange is primarily known for its fine fragrance, which smells a bit like oranges! A staple plant in fragrance gardens, mock oranges are even easier to enjoy if you plant them near a patio or other outdoor seating area where you can take in their sweet, sweet aroma at any time of the day.
But while there is much to love about mock oranges, if you want to keep these plants as happy as possible, don’t prune them in the fall. Like lilacs and forsythia, mock orange plants bloom on old wood, and fall pruning can limit how many flowers mock oranges will produce in spring. For this reason, it’s always best to prune mock oranges when the plant finishes flowering in early to mid-summer.
12. Viburnum (Viburnum spp.)
| Plant name: | Viburnum |
| Growing zone: | Zones 2 to 9 (most varieties) |
| When to prune: | Late winter to early spring or after flowering |
| Blooms on old wood? | Yes |
Most species of viburnum bloom on old wood, and autumn pruning can remove their flower buds and limit next year’s blooms. But if that wasn’t reason enough to put down your pruning shears, many species of viburnums produce berries in autumn, which make colorful additions to gardens when other plants have faded for the year. Late in autumn and winter, those berries also provide food for berry-eating birds, like finches, mockingbirds, and turkeys!
Many viburnum plants don’t need pruning at all, but if your viburnums do need reshaping, the best time to do it is after the plant flowers. When pruning viburnum shrubs, clip away old blooms and reshape the plant as needed by trimming back stems and scraggly branches with sharp shears or pruners. As with other plants, you can encourage viburnum to branch out and produce more flowers and leaves by making your pruning cuts right above a leaf node.
13. Lady’s mantle (Alchemilla mollis)
| Plant name: | Lady’s mantle |
| Growing zone: | Zones 3 to 8 |
| When to prune: | In summer, after flowering, or in spring |
| Blooms on old wood? | N/A |
Another cottage garden favorite, lady’s mantle, adds a feeling of classic elegance to garden beds with its airy, yellow flowers. But most gardeners keep lady’s mantle plants for their large, scalloped leaves, which add texture to landscape designs and catch morning dewdrops so that they shimmer in the light! Aside from their beauty, lady’s mantle are known for being low-maintenance plants, although lady’s mantle leaves can become sparse over time.
If your lady’s mantle has seen better days, you may want to consider pruning your plant. However, like Russian sage, lady’s mantle has a delicate crown, which can be vulnerable to winter damage if the plant is cut back closely in autumn. To avoid this, skip pruning these plants in autumn and cut lady’s mantle plants back in early spring before the plant begins to leaf out.
14. Ninebark (Physocarpus spp.)
| Plant name: | Ninebark |
| Growing zone: | Zones 3 to 9 |
| When to prune: | Late spring to early summer, after flowering |
| Blooms on old wood? | Yes |
Ninebark is one of the most popular winter interest plants, much loved for its exfoliating bark, which can add extra texture and movement to gardens in winter. Ninebark shrubs are also exceptional pollinator plants, and the plant’s blooms will attract native bees, as well as various species of butterflies and moths. On top of that, ninebark is an easy-going foundation plant that can anchor mixed ornamental beds and provide the perfect backdrop for smaller perennials and annuals.
But while ninebark is a great plant to try if you’re new to gardening (or even if you’re a seasoned gardening pro!), ninebark plants grow best if they’re pruned when the plant is dormant. That means you should avoid pruning ninebark in fall and, instead, prune the plant in winter when the plant is snoozing away! You can also prune ninebark plants immediately after their flowers fade in late spring to early summer.
15. Ornamental grasses
| Plant name: | Ornamental grasses |
| Growing zone: | Depends on variety |
| When to prune: | Late winter to early spring |
| Blooms on old wood? | N/A |
There are many different types of ornamental grasses, and some of them respond well to autumn pruning. Warm-season grasses, for instance, can sometimes handle fall pruning, but they often grow better when they’re cut back in spring. Cool-season grasses, however, are known to grow best when they’re cut back by up to two-thirds in early spring.
There are several different reasons why many ornamental grasses shouldn’t be pruned in fall. First, fall pruning can expose the roots of grass plants and make them more susceptible to winter damage. Aside from that, ornamental grasses are some of the most attractive winter interest plants you can find, and their seed heads feed wild birds in winter, while their slender stems provide cozy protection for hibernating pollinators and other small critters.
Frequently asked questions
Many perennial plants grow best when they’re pruned in spring. But one time you usually DO want to prune plants in fall is if you have plants that have struggled with pests or diseases during the growing season. Bee balm and peonies, for instance, are often pruned in the fall to limit the spread of powdery mildew.
While you may not need to prune certain perennials in fall, most plants will grow better if they receive some extra TLC in autumn. Mulching plants in fall can help to insulate plant roots and shelter delicate stems from the worst of winter weather. Some plants will also grow better if they’re wrapped in insulating burlap, while many plants will appreciate the extra nutrients from a late-season application of compost.
Yes. Daylilies, and lilies in general, are usually cut back in fall as their grass-like leaves can look unkempt if they’re left as is. It’s best to wait until after the first fall frost to prune back daylilies as plants that are pruned back too early in fall won’t be able to photosynthesize properly, and they can become weak over time.
That depends on the plant. Bushes that flower on old wood should usually be cut back in late spring to early summer after the plant finishes flowering. However, plants that have suffered from pest or disease damage may benefit from autumn pruning, which can limit the spread of diseases like mildew.
That depends on the plant and your growing zone. Some plants are more resilient to cold than others, but most plants will grow best if they’re pruned no later than 4 weeks before your first fall frost date. Pruning plants late in autumn can make them more vulnerable to cold damage.
Different plants are pruned in different ways, but in general, when plants are reshaped with pruning, old and leggy stems are pruned away, and pruning cuts are made immediately above a leaf node. Cutting plants above leaf nodes will encourage branching, leaf growth, and flowering, too! Flowering plants can also be cut back lightly by just pruning away their old, spent blooms – a process known as “deadheading.”
Summary
Pruning is often a flexible art, so if you see some plants on this list that you do prune in autumn, don’t be surprised. Many of the plants we’ve covered today will survive autumn pruning, but they may not grow and flower as abundantly if they’re cut back late in the season. Other plants that are recommended for fall pruning can also be pruned in spring, depending on your gardening style and how much time you can dedicate to pruning in any given season.
While keeping track of what plants need pruning can be tricky, it can help to remember that plants that flower in spring are usually pruned after they finish flowering, while plants that flower in fall are usually pruned in late winter to early spring. Again, this rule doesn’t apply to all perennials, but it’s a good tip to remember when you’re gardening on the go!
And if all this talk about pruning has inspired you to get out into your autumn garden, you may also enjoy our guide on perennial plants that should be divided in fall!
Granny Fish
Thank you for the guidance you put out for us amateurs. Much appreciated.
Lois
This is an amazing informative article! Thank you !! I'm sharing it with several family & friends. Look
Gardening Gal
Please retitle your article to say 15 Plants not 15 Perennials as quite a few of the Plants you discuss are shrubs not perennials. This will help reduce confusion amongst amateur gardeners. Thank you
Mary Ward
Shrubs (and trees) are perennials and many need to know when or if they should be cut back. We believe this to be an accurate title and important information.
https://www.britannica.com/science/perennial: "Trees and shrubs, including all gymnosperms (cone-bearing plants), are perennials, as are some herbaceous (nonwoody) flowering plants and vegetative ground covers."
Nan
Are you kidding? Half of the plants listed are shrubs that you wouldn’t cut back! And if you did cut them back it would be to prune in the spring after they have flowered!!! For instance, lilacs, rhodies, azalea! Do better research or hire a writer that actually gardens and grows plants for a living.
Mary Ward
Shrubs are perennials. Please see quotes and references in the other comment. The fact that they should be pruned in the spring to preserve buds and flowering is exactly why they are on this list of things that should not be cut back in the fall.
We welcome gardeners of all levels to this site, and recognize that this is information many beginner gardeners (and experienced, too) may be interested in learning.
The writer is also a certified Master Gardener. Future comments will need to maintain a more respectful tone to be approved.
Yara
As well as the roses you would only cut as they die
Teresa
Calm down.
Alex
Rohodies azaleas and viburnum are not perennials.
Mary Ward
All three are perennials. The definition of a perennial is a plant that lives for more than two growing seasons (some resources will say three). The fact that a plant is also a tree, shrub, evergreen, semi-evergreen, or deciduous does not mean that it is not also a perennial.
"Trees and shrubs, including all gymnosperms (cone-bearing plants), are perennials, as are some herbaceous (nonwoody) flowering plants and vegetative ground covers.": https://www.britannica.com/science/perennial
Like many other plants, they may not be perennials where you live if you live in a very cold or very warm climate where they are not native and/or which is outside their climate zone. However, these are hardy perennials that live even in most cold climates.
Here are three of many expert resources that list them as perennial:
"Rhododendrons are effortless perennials": https://parkseed.com/rhododendron/c/rhododendron/
"It is a dense, perennial shrub that can appear as a deciduous, evergreen, or semi-evergreen species...Viburnums grow in USDA hardiness zones 2–9, and can usually be planted in the fall or spring depending on your specific climate.": https://www.masterclass.com/articles/viburnum-guide
"Azaleas are perennial flowering shrubs, bearing flowers from March to June (depending on the variety).": https://www.gardenersworld.com/how-to/grow-plants/how-to-grow-azaleas/
Florence
Thank you very much! This is exactly what I was looking for since I have everything you listed besides the lilac. Now I know to leave them alone and to leave my dad's very out of hand rhodi alone, as well as his very old and sad lilac, until next year. I would have chopped away and done more harm than good.
It's very unfortunate that so many unsavory people have attacked this post. This is just my 2nd year of really gardening and wanting to know how to do things right to protect what I've invested so much time and money into growing. I have a lot to learn and I will be reading your other articles as I'm sure they will be just as helpful as this one is to me.
Mary, I appreciate you!
And as far as I'm concerned, if I don't have to plant it every year, then it's a perennial in my book!
Sincerely, Florence
East Central Illinois
Zone 5
Mary Ward
That's exactly it 🙂
Thanks for reading and thanks for the kind words and support. We look forward to having you back here!
Lyn Hinds
Appreciate the information and love that I can "help" my perennials
Rosellen Brittain
Love this info short and straight to the point.
Christopher Palazzoli, NYSCNP
This article was a little bit misleading. Although all these plants are perennial bloomers, some are considered “perennials” and others are “deciduous shrubs”. I was hoping to see a list of perennials that need to be cut back once per year to allow new growth from the crown for the following growing season. The shrubs that are mentioned never get cut down completely unless you are trying to rejuvenate old shrubs that have become overgrown and unshapely. It was a good article but could have been separated into 2 different categories.
Tim
Is it ok to trim down flox in the fall ?
Mary Ward
Phlox can go either way. Some say leave it for birds and insects (the seeds left by the flowers can feed birds and the stems help insects overwinter), others say cut it back to about three inches above the crown after a frost and after the phlox is dead.
One top reason to cut phlox back in the fall is that it is very prone to powdery mildew. If you noticed a lot of powdery mildew in your bed, it's smart to cut the old stems out in the fall to prevent it from coming back in spring. Burn the stems or bag and trash them instead of composting them.
Good luck!
Colleen
Thanks, Mary, for all the info but especially on properly disposing of powdery mildew. I have an old Phlox White David that I moved from a sunny S.W. cottage garden to the east side of our house. This year it was almost white with mildew & dropped leaves...not happy in its new home.
Mary Ward
You're welcome! I don't know about where you live, but here it was an extremely rainy summer. Powdery milder and fungal diseases were almost guaranteed. ...Which is to say, maybe it's the new location, but maybe it was the weather situation.