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When to Divide Perennials

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Use this handy guide to determine the best time to divide your garden perennials:


Botanical Name

Common Name

How Often To Divide

Season To Divide

Method Of Division



Every year or two to control spread and maintain vigor.


Spreading root division. Replant outer growth and discard the centers of older plants.


Every 2 to 3 years as plants become crowded. 

Early Spring or fall.

Spreading root division. Needs division for best bloom.
Bearded Iris


Every 3 to 4 years.

After flowering up to September.

Rhizome root division.


Every 3 years to control rampant growth. 

Spring or fall.

Spreading root division.


Every 2 to 3 years or as the plant becomes crowded. 

Spring or early fall.

Spreading root division.
Blackberry Lily


Every 3 to 4 years 

After bloom is finished.

Rhizomes should be treated as iris.
Black-eyed Susan

(Rudbeckia fulgida)

Every 3 to 4 years.

Early spring or fall.

Spreading root division.
Blanket Flower

(Gaillardia grandiflora)

Every 1 or 2 years to maintain vigor. 

Early spring.

Spreading root division.
Bleeding Heart


Rarely needs division. 

Early spring.

Fleshy root division. Be gentle with brittle roots.


Every 3 or 4 years, or as desired to increase stock. 


Fleshy root system.


Every year or two. 


Spreading root division.


Every 2 to 4 years. 

Spring or fall.

Spreading root division.


Every 3 to 6 years or as desired to increase stock. 

Spring, summer or fall. Ideal time is after bloom is finished.

Divide fleshy roots into segments with roots. Divisions with three or more shoots will bloom sooner.
Garden Peony


For plant increase, rarely needs division. Divisions may wait up to 3 years before blooming. 

September or October.

Divisions should have three to five well-developed eyes (buds for next year’s growth). Plant peonies with the eyes no deeper than 1 inch below the surface.
Garden Phlox

(Phlox paniculata)

Every 3 to 4 years. 

Early spring or fall.

Spreading root division.


Rarely need division and will reach their best form if not divided too often. They can be divided as needed for plant increase. 

Early spring or early fall.

Fleshy root division. Divide into clumps with one to three eyes. A wedge can be taken from an established plant, which will soon fill back in.

(Stachys byzantina)

Every 2 to 3 years. 

Spring or early fall.

Spreading divisions. Discard weak centers.
Lily of the Nile


When flowering slows due to crowding.

Spring, summer or fall

Fleshy clumping roots are large and brittle. Do not divide unless needed to improve bloom.
Lily of the Valley

(Convallaria majalis)

Divide for plant increase as desired. 

Early spring.

Can be divided as clumps or single "pips".
Ornamental Grasses Every 3 to 4 years. 

Spring for most grasses. Many grasses do not tolerate fall division.

Very dense fibrous root system may require the use of an ax or saw to divide.
Purple cone-flower


Every 4 years. 

Spring or fall.

Spreading root division.


Divide only for plant increase.

Spring or fall.

Fleshy clumping root system. Divisions may take 2-3 years to bloom.
Tall sedum

(Sedum ' Autumn Joy')

For plant increase. 


Clump divisions.


Every 1 or 2 years to maintain vigor. 

Spring or fall.

Spreading root division. Discard weak center.


Every year or two for spreading wormwoods like ‘Silver King’ and ‘Valerie Finnis.’ 


Spreading root division, or remove excess and dead center. Do not divide woody artemesias.


Every 2 or 3 years or when center dies out. 

Spring or fall.

Spreading root division.

Prepared by Karen Russ, HGIC Information Specialist & Bob Polomski, Extension Consumer Horticulturist, Clemson University 



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