Common Perennial Questions

Perennial Plants to Prune in the Fall
Bearded Iris The tall foliage of bearded iris begins flopping early in
the season. By fall, it’s cover for iris borers and fungal diseases. Cut back
after a killing frost and it would be wise to dispose of the foliage, rather
than composting
Beebalm (Monarda didyma) Even the most resistant varieties of Monarda can
succumb to mildew. When that happens, you’ll be cutting them back long before
fall. Fresh, new growth can be left on until spring. Sometimes selective
thinning of the stems is all that is needed and you can leave the remaining seed
heads for the birds.
Blanket Flower (Gaillardia x grandiflora) Gaillardia is a pretty hardy
plant, but cutting back the spent stems seems to improve its hardiness even
more, by improving its vigor.
Columbine (Aquilegia) Remove any foliage showing leaf miner damage and
remove any debris around the base of the plants. Aquilegia send out growth early
in spring and appreciate not having the old foliage to contend with.
Daylily (Hemerocallis) Daylilies respond well to shearing and unless you
are in an area where they remain somewhat evergreen, fall pruning will save you
a messy cleanup in the spring.
Peony (Paeonia) Peonies need a period of cold to set buds for the
following season. That coupled with the fact that their foliage is extremely
prone to mildew is reason enough to remove the foliage in the fall. Infected
foliage can be removed and disposed of in late summer. Healthy foliage will turn
golden in fall and can be removed once it has turned to mush, after the first
frost.
Phlox (Phlox paniculata) Phlox is prone toward powdery mildew. Even the
resistant varieties can become infected in bad weather. If so, prune and destroy
all foliage and stems in the fall.
Salvia (Salvia nemorosa) Perennial Salvia benefits from several prunings
during the growing season. In fall when blooming slows, cut the whole plant back
to the new basal growth.
Wild Indigo (Baptisia australis) Baptisia is one of those plants that
splits in the middle if not sheared back after pruning, however many gardeners
like the seed pods and simply stake the plants. Come frost, the foliage turns
black and even staking isn’t going to help its appearance. Cut back for
aesthetics.
Yarrow (Achillea) Achillea don’t like to sit in cold, wet soil. By fall,
most of their blooms are spent and the foliage is flopping and possibly
diseased. Cut back in early fall and new basil growth with fill in before frost.

Suggested Perennial Plants to
Prune in the Spring
Artemisia Most Artemisia don’t like being pruned in the fall. The growth
that results is too tender to survive the winter and the dieback is often enough
to kill the whole plant. Clean in early spring.
Asters Fall blooming asters have generally been pinched and forced
several times throughout the growing season. Once they are finally allowed to
bloom, they appreciate being left alone to recuperate, until spring. Several
bloom so late into the fall, the question of fall clean-up becomes moot.
Astilbe Astilbe don’t require much maintenance. Fall clean-up is
unnecessary and may weaken the plant’s tolerance for cold. Minimal spring
clean-up is required.
Balloon Flower (Platycodon grandiflorus) If pruned for sturdiness,
Balloon flower blooms late in the season and remains attractive until frost.
Since it is late emerging in the spring, it helps to leave the old foliage as a
marker.
Black-eyed Susan (Rudbeckia fulgida) Although not particularly attractive
in winter, the seed heads will feed the birds.
Butterfly Bush (Buddleia davidii) To lessen winter kill, wait for signs
of green at the base and then cut back to 6 - 10 inches.
Campanula Most campanulas get sheared back at some point during the
summer, to clean up ugly or damaged foliage and encourage another flush of
blooming. Fresh basal foliage will result and should be left through winter, so
as not to encourage more tender growth in the fall.
Coral Bells (Heuchera) Heuchera are prone to heaving in soils that freeze
and thaw. Leaving the foliage in tact helps to mulch the plants through winter.
Delphinium If you’re lucky enough to grow Delphiniums as perennials,
remove the flower stalks, but allow the foliage to remain until spring.
Dianthus Most Dianthus can remain somewhat evergreen throughout the
winter and nothing is gained by cutting back in the fall. They will still need
some clean-up in the spring.
Geum Geum can remain semi-evergreen throughout winter, so no fall pruning
is necessary, especially if you’ve been deadheading and cleaning up dead leaves
during the growing season.
Goldenrod (Solidago) The new hybrid goldenrods don’t seed or spread all
over the garden and can be left standing for winter interest. Study clumpers,
like ‘Fireworks’ and ‘Golden Fleece’, will remain upright through spring. The
old-fashioned species Solidago should be cut in fall, to avoid invasiveness.
Hosta Although Hosta foliage gets ugly over winter, some Hosta varieties
can be damaged by spring frosts and benefit from the protection of the collapsed
foliage.
Joe-Pye Weed (Eupatorium maculatum ) When a plant is bred from a common
weed, you can usually assume that it doesn’t need much care to survive. Joe-Pye
will bloom well into the fall and then produce fluffy seed heads. You can cut it
back if you choose, but it’s not necessary to the plant’s survival.
Lavender (Lavandula) Many areas have a hard time over-wintering lavender.
The problem is more often moisture than cold, but cold is a factor. Don’t prune
lavender late in the season, as new growth is extremely cold sensitive. Wait
until new growth appears in the spring before removing winter die back.
Lupine (Lupinus) Lupines are temperamental, short-lived perennials and
they do not enjoy winter. Leave the foliage on for protection and hope for the
best come spring.
Mums (Chrysanthemum) Leave the foliage in tact to protect the plant’s
crown. All the better to let the flowers bloom well into the fall.
Purple Coneflowers (Echinacea purpurea) Coneflowers don’t look terribly
attractive in winter, but they do attract and feed birds. If you’d like both
birds and aesthetics, you can always prune your coneflowers in July and get
squat, sturdy plants that will provide seed and remain standing.
Russian Sage (Perovskia atriplicifolia) Like its cousin Lavender,
Perovskia doesn’t like to be trimmed back in that fall, because it’s tender
growth is too sensitive to cold. Wait until new growth appears in the spring and
then cut back to about 6 - 8". If the only new growth is from the base of the
plant, the entire top woody section has died back and it can be pruned to the
ground.
Sedum Many of the tall Sedums can remain attractive throughout the
winter, even holding caps of snow on their flower heads. ‘Autumn Joy’, in
particular, holds up very well. The basal foliage appears very early in spring,
so Sedum can be one of the first plants you prune in the spring.
Tickseed (Coreopsis) Like Chelone, most coreopsis seem to fare better if
allowed to stand during the winter and cleaned-up in the spring.
Roses
We receive a lot of questions about caring for roses, especially about pruning. Here are a few tips regarding roses.
When to Prune Roses
Timing is determined by the class of the rose plant and
the zone in which it is growing. Most rose pruning is done in the spring, with
the blooming of the forsythia as a signal to get moving. If you don't have
forsythia, watch for when the leaf buds begin to swell on your rose plants,
meaning the bumps on the canes get larger and reddish in color.
Hybrid tea roses are the most particular about pruning. If you don't know
what type of rose you have, watch the plant for a season. If it blooms on the
new growth it sends out that growing season, prune while dormant or just about
to break dormancy, as stated above. If it blooms early, on last year's canes,
don't prune until after flowering.
Some general pruning guidelines by rose classification:
BLOOMS ONCE, ON NEW GROWTH
Modern Ever-Blooming Roses & Floribunda: These bloom best on the
current season's growth. Prune hard (½ to 2/3 the plant's height) in the spring
and remove old woody stems. Leave 3-5 healthy canes evenly spaced around the
plant. Cut them at various lengths from 18 - 24 inches, to encourage continuous
blooming.
Hybrid Teas & Grandiflora: These also bloom on new wood and should
be pruned in early spring. Remove dead and weak wood. Create an open vase shape
with the remaining canes by removing the center stems and any branches crossing
inwards. Then reduce the length of the remaining stems by about ½ or down to 18
- 24 inches. You can allow the older, stronger stems to be a bit longer than the
new growth.
BLOOMS ONCE, ON OLD WOOD
Ramblers: Prune to remove winter damage and dead wood or to shape and
keep size in check. Ramblers bloom only once and can be pruned right after
flowering, all the way back to 2-3 inches if you wish.
REPEAT BLOOMERS
Modern Shrub Roses: This group is repeat bloomers, blooming on mature,
but not old, woody stems. Leave them unpruned to increase vigor for the first 2
years and then use the "one-third" method. Each year remove one-third of the
oldest canes (in addition to any dead, diseased or dying canes).
Climbers: Climbers may repeat bloom. Prune early to remove winter
damage and dead wood. Prune after flowering to shape and keep their size in
check.
MINIMAL PRUNING NEEDED
Alba, Centifolia, Damasks, Gallica, and Mosses: This group blooms only
once, producing flowers on old wood and don't require much pruning at all. Prune
only to remove dead or thin wood and to shape the plants and prune after
flowering.
Miniature Roses: Prune only to shape. Cut back to an outward facing
bud after blooming.
Rose Pruning Basics
- Use clean, sharp tools
- Look at the overall plant, but begin pruning from the base of the plant.
- Prune to open the center of the plant to light and air circulation
- Make your cuts at a 45-degree angle, about 1/4 inch above a bud that is
facing toward the outside of the plant.
- Make sure it is a clean cut (not ragged)
- Remove all broken, dead, dying or diseased wood (Any branches that look dry,
shriveled or black. Cut until the inside of the cane is white.)
- Remove any weak or twiggy branches thinner than a pencil
- If cane borers are a problem in your area, seal the cut with a white glue,
such as Elmer’s.
- Remove sucker growth below the graft.
- Remove any remaining foliage