Dividing Perennials
Scientific name
Name
How often to divide
When to divide
Achillea spp.
Yarrow
1 to 3 years
Spring
Separate by cutting or pulling apart. Discard central woody core.
Acontium napellus
Monkshood
10+ years
Spring
Resents disturbance. Due to poisonous nature of roots, use rubber gloves when dividing tuberous roots.
Adiantum pedatum
Maidenhair Fern
Spring
Aegopodium podagraria 'Variegatum'
Snow-on-the-Mountain
1 to 3 years
Spring or Fall
Ajuga reptans
Bugleweed
1 to 3 years
Spring or Fall
Can be divided any time of year, but spring and fall are best for quick rooting.
Alchemilla mollis
Lady's Mantle
6 to 10 years
Spring (or Early Fall)
Cut crown into sections with sharp spade or knife.
Allium spp.
Ornamental Onion
Fall
Divide overcrowded clusters after foliage disappears. Plant "new" bulbs in fall.
Anemone spp.
Anemone
10+ years
Spring
Resents disturbance.
Aquilegia spp.
Columbine
10+ years
Spring (or Late Summer)
Does not like to be disturbed. Dig deep to get all tapering, finger-like roots. Cut youngplant apart with a sharp knife.
Arisaema triphylla
Jack-in-the-Pulpit
Fall
Divide offsets when plant is dormant
Armeria spp.
Thrift
4 to 5 years
Spring
Artemisia spp.
Artemisia
4 to 5 years
Spring
Regular division is important for health of plant and helps keep its invasive nature under control. Discard weak central crown.
Aruncus dioicus
Goats Beard
10+ years
Spring or Fall
Deep rootstock resents disturbance. Use knife to cut woody crown.
Asarum spp.
Ginger
6 to 10 years
Spring or Early Fall
Use sharp knife to cut rhizome.
Asclepias spp.
Milkweed
10+ years
Does not like to be disturbed. Dig deep to avoid damaging deep taproots. Cut crown apart with sharp knife. Rootstocks are brittle.
Aster spp.
Aster
1 to 3 years
Spring or Fall
Many cultivars require frequent division and replanting of small, healthy pieces from the outside of the clump.
Astilbe x arendsii
Astilbe
1 to 3 years
Spring (or Fall)
Needs division for best bloom. Cut plant into sections with sharp spade or knife.
Astrantia spp.
Masterwort
4 to 5 years
Spring or Fall
Divide with spade or pitchfork.
Athyrium filix-femina
Lady Fern
Spring or Fall
Use sharp knife to cut rootstock.
Athyrium niponicum
Japanese Painted Fern
Spring or Fall
Use sharp knife to cut rootstock.
Aubrieta deltoidea
Rockcress
Spring
Aurinia saxatilis
Basket of Gold
Spring
Difficult because plants clump
Baptisia australis
False Blue Indigo
10+ years
Spring
Resents disturbance. Dig deep to remove entire root system without breaking it. Cut crown apart with sharp knife or saw.
Bergenia cordifolia
Heart Leaf Bergenia
4 to 5 years
Spring or Summer
Cut rhizome with sharp knife. Transplant divisions fairly deep into soil.
Boltonia asteroides
Boltonia
4 to 5 years
Spring or Early Fall
Brunnera macrophylla
False Forget-me-not
6 to 10 years
Spring or Fall (Late Summer)
Caltha palustris
Marsh Marigold
After flowering - May or June
Campanula spp.
Bellflower
4 to 5 years
Spring or Late Summer (August)
Cut thick, fleshy rootstock apart with sharp knife.
Carex spp.
Sedge
Spring
Divide with spade or pitchfork.
Catanache caerulea
Cupid's Dart
1 to 3 years
Fall or Spring
Centaurea montana
Cornflower
1 to 3 years
Spring (or Fall)
Cerastium tomentosum
Snow-in-summer
1 to 3 years
Spring or Fall
Can be divided virtually anytime.
Chelone spp.
Turtlehead
4 to 5 years
Spring
When young offshoots are 1" high, dig with spade to sever from parent plant.
Cimicifuga racemosa
Snakeroot or Bugbane
10+ years
Spring
Resents disturbance. Cut plant into sections with sharp knife or spade. Discard old, woody, central clump.
Clematis spp.
Clematis
10+ years
Spring
Divisions on only selected species. Cut crown apart with sharp knife or spade.
Convallaria majalis
Lily of the Valley
Spring or After Flowering
Divide to keep invasive nature under control.
Coreopsis
Tickseed
1 to 3 years
Spring (or Early Fall)
Cut crown apart with sharp knife. Coreopsis grandiflora and Coreopsis lanceolata live longer if divided every 2 to 3 years.
Delphinium grandiflorum
Delphinium
1 to 3 years
Spring
Fall-dug plants often die over winter. Regular division can prolong their life.
Dendranthema x grandiflora
Garden Mum
Every year
Spring
Will survive longer and be most vigorous if divided and replanted every spring. Discard central core.
Dianthus spp.
Pinks
1 to 3 years
Spring
Dividing every few years can often extend longevity.
Dicentra spp.
Bleeding Heart
6 to 10 years
Spring
Cut crown apart with sharp knife. Roots are brittle, so handle carefully.
Dictamnus albus
Gas Plant
10+ years
Divisions are difficult due to crown damage. A spade plunged straight down through the plant's center, cutting the roots cleanly without severe bruising gives best results.
Dodecatheon meadia
Shooting Star
Fall (or Spring)
Echinacea purpurea
Purple Coneflower
4 to 5 years
Spring (or Early Fall)
Can remain undisturbed for years. Divide every 4 to 5 years for plant's health. Cut crown apart with sharp knife.
Echinops ritro
Globe Thistle
6 to 10 years
Spring (or Fall)
Resents disturbance.
Epimedium x rubrum
Red Barrenwort
6 to 10 years
Spring or fall
If conditions are favorable, can be left undisturbed for years.
Eupatorium purpureum
Joe Pye Weed
1 to 3 years
Spring to Summer/Early Fall
Use knife to slice woody crown.
Euphorbia polychroma
Cushion Spurge
10+ years
Spring (or Fall)
Discard central woody clump. Roots of some spurges are brittle, so handle carefully.
Gaillardia x grandiflorum
Blanket Flower
3 to 5 years
Spring or Fall
Divide by hand.
Galium odoratum
Sweet Woodruff
Spring (or Fall)
Divide by hand.
Geranium spp.
Cranesbill
6 to 10 years
Spring (or Early Fall)
Some varieties can be pulled apart by hand while others will need to be cut apart with a sharp knife.
Geum triflorum
Prairie Smoke
1 to 3 years
After flowering in late Summer
Grasses
Spring
Most grow well for years without division. Discard old, central portion of crown. Use sharp knife or spade to divide smaller grasses; use hatchet or ax on large grasses
Gypsophila paniculata
Baby's Breath
10+ years
Deep taproots resent disturbance. Double-flowered cultivars are grafted and, therefore, cannot be divided
Helenium autumnale
Sneezeweed, Helen's Flower
1 to 3 years
Spring (or Fall)
Helianthus spp.
Sunflower
1 to 3 years
Spring or Fall
Regular division improves performance and keeps invasive nature under control.
Heliopsis helianthoides
False Sunflower
5 to 10 years
Spring (or Fall)
Cut crown apart with sharp knife. Discard old central portion.
Helleborus orientalis
Lenten Rose
10+ years
Spring
Divide while plants are in bloom or immediately after they stop flowering.
Hemerocallis spp.
Daylily
3 to 5 years
Spring or immediately after flower
Division promotes heavier bloom.
Heuchera sanguinea
Coral Bells
1 to 3 years
Spring (or Fall)
Cut crown apart with sharp knife. Discard old, woody, central portion.
Hibiscus moscheutos
Rose Mallow, Hibiscus
10+ years
Spring or Fall
Plants are slow to send up shoots in spring, so fall division might be easier.
Hosta spp.
Hosta
6 to 10 years
Spring or Fall
If center of plant begins to get bare, cut out center and discard.
Hyssopus officianalis
Hyssop
Spring
Carefully divide woody roots.
Iris spp.
Bearded Iris
1 to 3 years
4 to 6 weeks after flowers are finished blooming
Fewer blooms indicate need for rejuvenation. Use a sharp knife to cut rhizome. Discard older part of plant.
Iris siberica
Siberian Iris
6 to 10 years
Spring* or Late Summer/Early Fall**
*In spring divide before leaves are 3" to 4" tall. Dividing too late can stop bloom for an entire season. **In early fall, cut leaves back to 6" to 12" and then divide. Use sharp knife to cut rhizome.
Lamiastrum galeobdolen
Golden Deadnettle
Spring or Fall
Lamium maculatum
Spotted Dead Nettle
4 to 5 years
Spring
Can also be divided mid-summer if cut back and watered well while taking root.
Lathyrus latifolius
Perennial Sweet Pea
10+ years
Spring
Does not like to be disturbed.
Leucanthemum x superbum
Shasta Daisy
1 to 3 years
Spring (or Fall)
Regular division can extend their life. Discard old central portion.
Liatris spicata
Blazing Star, Gayfeather
3 to 5 years
Spring
Cut into sections with sharp knife.
Ligularia spp.
Ligularia
6 to 10 years
Spring or Fall
Lilium
Lily
Late Summer / Early Fall
There are so many types of lilies, a whole book could be dedicated to how to divide each type.
Limonium platyphyllum
Sea Lavender
Spring or Early Fall
Carefully divide long roots.
Linum perenne
Flax
10+ years
Spring (or Early Fall)
Does not like to be disturbed. Dividing long, tangled roots is chancy.
Liriope spicata
Creeping Lilyturf
Spring or Fall
Use division to keep invasive nature under control.
Lobelia cardinalis
Cardinal Flower
1 to 3 years
Spring or Fall
Discard old central, woody clump.
Lupinus 'Russell Hybrids'
Russell Hybrid Lupine
10+ years
Spring
Does not like to be disturbed.
Lysimachia spp.
Loosestrife
6 to 10 years
Spring (or Fall)
Malva alcea 'Fastigiata'
Hollyhock Mallow
1 to 3 years
Spring or Fall
Matteuccia pensylvanica
Ostrich Fern
Spring
Mentha spp.
Mint
3 to 5 years
Spring or Fall
Use division to keep invasive nature under control.
Mertensia virginica
Bluebells
3 to 4 years
Spring
Monarda didyma
Bee Balm
1 to 3 years
Spring
Discard old central clump.
Myosotis spp.
Forget-me-Not
Spring
Divide by hand.
Nepeta spp.
Catmint
*Spring
Cut into sections with sharp knife or spade. * Can also be divided after primary bloom period if cut back and watered carefully.
Oenothera spp.
Sundrops, Evening Primrose
*10+ years
Spring (or Fall)
Most species do not divide well. Oenothera fruticosa needs to be divided every 1 to 3 years.
Onoclea sensibilis
Sensitive Fern
Spring (or Fall)
Osmunda spp.
Fern - Cinnamon
Spring
Pachysandraterminalis
Japanese Spurge
Spring
Paeonia sp.
Peony
10+ years
Early Fall Mid-August / September
Does not like to be disturbed. Dig around plant & slit roots with sharp spade. Roots are thick and brittle. Replanting too deep can diminish flowering.
Papaver orientale
Oriental Poppy
6 to 10 years
Mid- to Late Summer
Resents disturbance.
Penstemon digitalis
Smooth Penstemon
1 to 3 years
Spring
Divide with spade or pitchfork.
Perovskia atriplicifolia
Russian Sage
10+ years
Spring or Fall
Does not like to be disturbed.
Phlox paniculata
Tall Phlox
2 to 4 years
Spring (or Late Summer)
Discard central core if woody or dead.
Phlox subulata
Creeping Phlox
1 to 3 years
Spring or Early Fall
Use only non-woody stems.
Physostegia virginiana
Obedient Plant
1 to 3 years
Spring
Platycodon grandiflorus
Balloon Flower
10+ years
Spring
Does not like to be disturbed. Will not bloom for a year or two after division. Handle brittle root system carefully.
Polemonium coeruleum
Jacob's Ladder
6 to 10 years
Spring
Divide by hand.
Polygonatum odoratum
Solomon's Seal
6 to 10 years
Spring or Fall
Slice through knobby rootstock with knife.
Polygonum cuspidatum
Fleeceflower
Spring or Fall
Primula sp.
Primrose
Spring after flowering or Early Fall
Divide by hand.
Pulmonaria spp.
Lungwort
6 to 10 years
Spring after flowering (or Fall)
Water regularly following division
Pulsatilla vulgaris
Pasque Flower
10+ years
Spring or Fall
Does not like to be disturbed. Fragile roots may die if bruised.
Rheum palmatum
Ornamental Rhubarb
Spring
Use sharp knife to cut rootstock. Make sure each division has a dormant eye (crown bud).
Rudbeckia spp.
Black Eyed Susan
4 to 5 years
Spring (or Fall)
Divide with spade or pitchfork.
Salvia spp.
Sage
6 to 10 years
Spring (or Fall)
When plant dies out in center, it's time to divide.
Sanguisorba obtusa
Burnet
4 to 5 years
Spring or Late Summer
Saponaria ocymoides
Soapwort
Any time during warmer months
Scabiosa columbaria
Pincushion Flower
4 to 5 years
Spring
Division is a reliable but slow method of propagation.
Sedum spp.
Stonecrop
4 to 5 years
Spring
Divide by hand.
Sempervivum tectorum
Hen & Chicks
Spring or Fall
Separate small outer rosettes from parent plant.
Sidalcea spp.
Dwarf Hollyhock, False Mallow
1 to 3 years
Spring or Fall
Solidago spp.
Goldenrod
4 to 5 years
Spring or Fall
Divide with spade or pitchfork.
Stachys byzantina
Lamb's Ears
4 to 5 years
Spring (or Fall)
Divide by hand.
Tanacetum coccineum
Painted Daisy
1 to 3 years
Spring or Late Summer
Thalictrum spp.
Meadow Rue
6 to 10 years
Spring
Most species are slow to recover after division.
Thermopsis spp.
False Lupine
10+ years
Spring
Resents disturbance. Only divide when plants are several years old.
Thymus spp.
Thyme
4 to 5 years
Spring
Tiarella wherryi
Foamflower
1 to 3 years
Spring (or Fall)
Divide by hand.
Tradescantia x andersoniana
Spiderwort
3 to 5 years
Spring (until flowers set)
Division is only way to ensure duplication of cultivars.
Tricyrtis hirta
Toad Lily
6 to 10 years
Spring
Trillium grandiflorum
Trillium
10+ years
Spring or Late Summer
Does not like to be disturbed.
Trollius chinensis
Globe Flower
Fall
Slow to recover from transplanting.
Veronica spp.
Speedwell
3 to 5 years
Spring or Early Fall
Veronicastrum virginicum
Culver's Root
4 to 5 years
Spring or Late Summer
Vinca minor
Periwinkle
Spring or Fall
Viola spp.
Violet
Spring or Fall
Divide by hand.
Waldsteinia ternata
Barren Strawberry
Spring (or Early Fall)
Division is safest when plant is not blooming.
Yucca filamentosa
Adam's Needle, Ivory Tower, Yucca
10+ years
Resents disturbance. Divide only young plants. Established plants have deep, thick roots.