Divide midsummer to fall bloomers in early spring.
In Chester County, do most of your divisions in
spring to give new plants time to get established
before cold weather arrives.
Division Techniques
One in a series of informational brochures produced by the
Penn State Extension Master Gardeners of Chester County,
sponsored by Penn State University’s Cooperative Extension.
Penn State Extension Master Gardeners are volunteers who
educate the public on best practices in consumer horticulture
and environmental stewardship. They receive horticultural
training from Penn State University’s College of Agricultural
Sciences Cooperative Extension.
To divide, lift the plant with a spade or fork, being
careful not to damage the roots. Shake off the soil
and tease the sections of the clump apart. Hose soil
off, if necessary.
For answers on any home gardening issue, call the Master Gardener
Hotline at 610-696-3500 or email [email protected].
If the clumps have thick, entwined roots and resist
separation, use an old butcher knife, an ax, or a
sharp spade to cut the clump into pieces. Place
your cuts so that each division has a lot of roots.
Penn State Extension Master Gardeners
Government Services Center
601 Westtown Road, Suite 370
West Chester, PA 19380-0990
610-696-3500
[email protected]
Chester.extension.psu.edu
If you have a plant in which the center has died
out, cut away the woody center and divide the
outer ring of healthy growth.
Revised in March 2011 fro m materia l supplied by Penn State
Extension Master Gardeners Berks County.
Replanting Divisions
Replant those divisions that have strong, healthy
root systems. When dividing in spring before
plants start putting out new growth, replant the
divisions immediately. If the plants have already
produced full stems and leaves, remove 1/2 to 2/3
of the foliage before replanting. This is done
because the reduced root system is now unable to
replace the amount of water lost through the larger
top plant growth. Replant slightly higher to allow
the plant to settle, firm the soil around the plant,
water well, but do not wash soil from around roots.
If you can’t replant immediately, keep the divisions moist and protected from the hot sun and
drying winds.
If you have a question about any gardening
problem or procedure, call the Penn State Extension Office.
Penn State College of Agricultural Sciences research and extension
programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.
Visit Penn State Extension on the web: extension.psu.edu
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Dividing
Perennials
Why Divide Perennials?
Multiply by Dividing
Division is the easiest and most common method
of increasing perennials. Most perennials respond
well to division, which is done to keep rampantly
growing plants in bounds, as well as to keep older
plants looking good as the clump-forming center
dies. Dividing is a surefire way to expand and
strengthen your stock.
Division is good economics and lots of fun, if you
observe the rules of propagation: WHEN to divide
(spring or autumn), WHERE to plant (sun or
shade), and HOW to divide plants. The best seasons for dividing are autumn and spring. Autumn
planting allows plants to establish while the soil is
still warm enough for good root growth. Spring
planting is better for perennials NOT fully hardy or
for those that dislike wet winter conditions. Do not
divide perennials into very small pieces, as they
will need several years to mature.
Time to Divide
Divide perennials when they are growing but not
blooming. Divide spring- and early summerblooming perennials in late summer to early fall.
When to Divide
Spring
How to Divide
Divide regularly. Each division becomes a mature, flowering plant in one season.
Cut to ground after bloom in late October and enrich soil with compost or manure to several inches.
Where to Plant
Full sun/
light shade
Astilbe
Early spring, before foliage
unfolds; also late summer
Dappled shade/sun if
kept watered
Chrysanthemum
Spring
After first killing frost, cut plants to ground or leave in place for spring clean-up. Divide every 3 to 4
years. Dig up crown. Shake free of soil. Rinse roots around crown with water. Cut through center of
crown with knife. Should have 3-4 “eyes” (buds) in each section.
Replant sections at same height as original crown.
Divide roots. Stem cuttings. Take cuttings in early spring or late winter.
Coneflower
Spring/fall
Uproot clump. Cut in segments with knife.
Sun
Coral Bells
Spring/early fall
Remove clump with fork. Divide using young, outer parts of the crown.
Sun/light shade
Coreopsis
Spring/fall
Fall pruning. Cut off at ground. Lift with spade or fork. Divide with spade or knife.
Full sun
Daylilies
Spring/early fall
Divide every few years in spring or fall. Dig up clump; trim foliage to 5-8” of crown.
With knife, pull clump apart so each division has at least one “fan” of leaves. Replant.
Sun
Dianthus
Spring or after bloom
Divide with knife or pull apart
Sun
Ferns
Spring
Shade
Hosta
Early spring; also summer
and late fall
Divide clumps when growth begins in spring.
Cut through clumps with knife, leaving separate crown that can grow new fronds.
Dig up clump. Pull rhizomes apart. Separate with knife, leaving abundant roots on each cluster.
Each division must have at least one bud.
Iris
After bloom
(July/August)
Early spring/fall
Dig out clump with spade. Use knife to cut apart rhizomes. Divide when iris cluster is full.
When replanting, barely cover rhizome.
Break apart clump. Use knife or spade to divide.
Full sun
Rudbeckia (blackeyed Susan)
Spring
Divide roots with knife after lifting with fork or spade.
Sun/light shade
Sedum
Spring or after bloom
Mid-April separate new growth. Divide with knife and pull apart. Set high.
Sun/part shade.
Thyme
Mid-spring/fall to
early summer
Cut heavily in spring to woody stem. Also cut up to October, but no more than 1/3 maximum.
Divide (they break apart easily)
Full sun/
partial shade
Yarrow
Spring and
after bloom
Root division. Divide in half (or more if it has some age on it) with knife. Divide or replant every third
year. Set plant high when replanting.
Full sun
Yucca
Spring/fall
Use sharp knife or garden fork to break offsets from main plant.
Sun
Plant
Aster
Lavender
Sun/lightshade
Shade/
light sun
Full sun