When to Divide Perennials

Aster – Divide every 2-3 years in spring

Astilbe – Divide every 3-4 years in spring

Baby’s Breath (Gypsophila) – Division is difficult, carefully divide in spring or late summer/early fall

Basket-of-Gold (Aurinia) – Divide in late summer/early fall. 

Bee Balm (Monarda) – Divide approx. every third year in spring

Blanket Flower (Gaillardia) – Divide in spring

Blazing Star (Liatris) – Divide in spring

Bleeding Heart (Dicentra) – Division is difficult, best done in late summer/early fall

Butterfly Weed (Asclepias) – A taproot makes division difficult.  Easily propagated by seeds

Chrysanthemum – Divide every 2-3 years in spring

Columbine (Aquilegia) – Many species and varieties are short lived. Division is difficult,
carefully divide in late summer

Coral Bells (Heuchera) – Divide in spring or late summer/early fall

Coreopsis – Divide in spring or late summer/early fall

Cornflower (Centaurea) – Requires division every 2-3 years.  Divide in spring

Daylily (Hemerocallis) – Divide in spring or late summer/early fall

Delphinium – Usually short-lived , division is seldom necessary

False Indigo (Baptisia) – Division is difficult because of its long taproot.  Plants can be started from seeds

Gooseneck Loosestrife (Lysimachia clethroides) – Plants spread aggressively.  Divide every 2-3 years in spring

Hardy Geranium (Geranium) – Divide in spring or late summer/early fall

Ox Eye (Heliopsis) – Divide every other year in spring or late summer/early fall

Hosta – Plants can be left undisturbed for years.  If additional plants are desired, divide clumps in spring or late summer/early fall

Iris, Bearded (Iris germanica) – Divide every 3-4 years in July or August

Iris, Siberian (Iris sibirica) – Divide after blooming in early summer

Lily of the Valley (Convallaria) – A rapidly spreading groundcover, divide in spring

Lungwort (Pulmonaria) – Divide in late summer/early fall

Obedient Plant (Physostegia) – Plants spread rapidly.  Divide plants every 2-3 years in spring

Oriental Poppy (Papaver) – Divide when plants die back in mid to late summer

Ornamental Grass – The best time is spring. Also can be divided in late summer/early fall

Peony – Peonies are long-lived and can be left undisturbed for years.  If additional plants are
desired, divide clumps in September

Perennial Salvia (Salvia) – Divide plants in spring

Phlox, Garden (Phlox paniculata) – Divide every 3-4 years in spring or late summer/early fall

Phlox, Moss (Phlox subulata) – Divide plants in spring immediately after blooming

Purple Coneflower (Echinacea) – Divide every 3-4 years in spring

Shasta Daisy (Leucanthemum) – Tends to be short-lived.  Divide plants in spring

Speedwell (Veronica) – Divide in spring or late summer/early fall

Spiderwort (Tradescantia) – Divide every 2-3 years in spring

Stonecrop (Sedum) – Divide in spring

Yarrow (Achillea) – Many of the Yarrows spread rapidly.  Divide every 3-4 years in spring