How often should a perennial be divided?

Each perennial has a different length of time that they need to grow before being divided. Some prefer not to be divided at all.

Some perennials need division frequently, while others do better if left undisturbed.  The list below illustrates how often to divide many common perennials.  These recommendations assume suitable growing conditions and overall healthy plants.  Note:  The time frames given for division are those required to maintain plant health.  Some of the plants on this list can be invasive under certain conditions and may need division more frequently than indicated if their size must be limited.

(*Indicates those plants that do not like to be disturbed and will reestablish themselves slowly.)

Plants that need division every 1-3 years:

Achillea (Yarrow)

Boltonia

Phlox

Anchusa (Bugloss)

Dendranthema (Daisy)

Physostegia (Obedient Plant)

Anthemis (Hardy Marguerite)

Delphinium

Primula (Primrose)

Artemisia (Wormwood)

Iris (Bearded)

 

Aster

Monard (Bee Balm)

 

Plants that need division every 4-5 years:

Armeria (Sea Thrift)

Dicentra eximia (Wild Bleeding Heart)

Lilium (Lilly)

Astilbe

Echinacea (Coneflower)

Rudbeckia (Black-Eyed Susan)

Campanula (Bellflower)

Erigeron (Fleabane)

Scabiosa (Pincushion Flower)

Centaurea(PerennialCornflower)

Helenium (Sneezeweed)

Solidago (Goldenrod)

Chelone (Turtlehead)

Heuchera (Coralbells)

Stachys (Lamb’s Ears)

Coreopsis (Tickseed)

Liatris (Blazing Star)

Veronica (Speedwell)

Plants that need division every 6-10 years or do not like to be disturbed:

Alchemilla (Lady’s Mantle)

Geranium (Cranesbill)

Nepeta (Catmint)

Amsonia*(Bluestar)

Hemerocallis (Daylily)

Polygonatum (Solomon’s Seal)

Brunnera (Siberian Bugloss)

Hosta

Pulmonaria (Lungwort)

Cassia* (Wild Senna)

Iberis* (Candytuft)

Salvia (Meadow Sage)

Cimicifuga* (Snakeroot)

Iris (Siberian Iris)

Sedum (Stonecrop)

Echinops* (Thistle)

Ligularia

Thalictrum (Meadow Rue)

Epimedium* (Bishop’s Hat)

Limonium (Statice)

Trollius* (Globe Flower)

Filipendula (Meadowsweet)

Lysimachia (Loosestrife)

Ornamental Grasses

Plants that need division only every 10 or more years:

Aconitum (Monkshood)

Dictamnus (Gas Plant)

Paeonia (Peony)

Anemone (Windflower)

Eryngium (Sea Holly)

Papaver (Poppy)

Aruncus (Goatsbeard)

Euphorbia (Spurge)

Platycodon (Balloon Flower)

Asclepias (Butterfly Weed)

Gypsophila (Baby’s Breath)

Thermopsis (False Lupine)

Baptisia (Wild Indigo)

Hibiscus

 

Dicentra spectabilis(BleedingHrt)

Kirengeshoma