Dividing Perennials is a great way to keep plants healthy and make more room for other plants. You can also get two, three or even 4 plants for the price of one. When you divide is important. The S below means spring, the F is for fall dividing.
A few key points.
· Keep Plants in the same light and soil conditions they enjoyed or move them to better suited areas.
· Don’t plant them any deeper than they were in the ground.
· Water the perennial until they are reestablished.
· Don’t over fertilize. This can harm the roots and the overall health of the plant.
· Leave enough space for the plant to grow, remember how big it was before you divided it? It will likely be that size again in 3 years.
According to Fine Gardening, the following is a list of when to divide some of the more common perennials.
These Perennials Should Be Divided By Hand
- Blanket flowers (Gaillardia spp.) S/F
- Bleeding hearts (Dicentra spp.) S Divide After Flowering
- Bugleweed (Ajuga reptans) S/F
- Columbines (Aquilegia spp.) S/F
- Coral bells (Heuchera spp.) S/F
- Cranesbills (Geranium spp.) S/F
- Creeping Jenny (Lysimachia nummularia) S/F
- Deadnettle (Lamium maculatum) S/F
- Epimediums (Epimedium spp.) S Divide After Flowering /F
- Foam flower (Tiarella cordifolia) S/F
- Forget-me-not (Myosotis sylvatica) S Divide After Flowering /F
- Hellebores (Helleborus spp.) S Divide After Flowering /F
- Jacob's ladder (Polemonium caeruleum) S/F
- Lady's mantle (Alchemilla mollis) S/F
- Lamb's ears (Stachys byzantina) S/F
- Moss pink (Phlox subulata) F
- Primroses (Primula spp.) S Divide After Flowering
- Pulmonarias (Pulmonaria spp.) S Divide After Flowering /F
- Pussytoes (Antennaria dioica) S/F
- Sea thrift (Armeria maritima) S/F
- Speedwell (Veronica spicata) S/F
- Spurge (Euphorbia myrsinites) S/F use gloves
- Stonecrop (Sedum spectabile) S/F
- Sweet woodruff (Galium odoratum) F
- Violets, pansies (Viola spp.) S/F
- Wormwood (Artemisia ludoviciana) S/F
- Yarrow (Achillea millefolium) S/F
Use A Spade or Pitchfork To Divide These
- African lilies (Agapanthus cvs.) S/F
- Anemone (Anemone X hybrida) S
- Asters (Aster spp.) S
- Bee balm (Monarda didyma) S/F
- Bellflowers (Campanula spp.) S/F
- Big bluestem grass (Andropogon gerardii) S/F
- Black-eyed Susans (Rudbeckia spp.) S/F
- Blood grass (Imperata cylindrica) S/F
- Cardinal flower (Lobelia cardinalis) S/F
- Catmint (Nepeta X faassenii) S/F
- Coneflower (Echinacea purpurea) S/F
- Daisy (Leucanthemum X superbum) S/F
- Daylilies (Hemerocallis spp.) S/F
- Forest grass (Hakenochloa macra) S/F
- Fountain grass (Pennisetum alopecuroides) S/F
- Garden phlox (Phlox paniculata) S/F
- Gaura (Gaura lindheimeri) S/F
- Goldenrods (Solidago spp.) S/F
- Gunnera (Gunnera manicata) S/F
- Hostas (Hosta spp.) S/F
- Japanese painted fern (Athyrium niponicum 'Pictum') S/F
- Jerusalem sage (Phlomis russeliana) S/F
- Lemon balm (Melissa officinalis)
- Ligularia (Ligularia dentata) S/F
- Masterwort (Astrantia major) S/F
- Monkshood (Aconitum napellus) S
- Penstemons (Penstemon spp.) S/F
- Perennial sage (Salvia X superba) S Divide After Flowering /F
- Pinks (Dianthus plumarius) S/F
- Poppies (Papaver spp.) F
- Red hot pokers (Knifophia spp.) S/F
- Sedge (Carex morrowii) S/F
- Siberian iris (Iris sibirica) F
- Silver grasses (Miscanthus spp.) S/F
- Snakeroot (Cimicifuga racemosa) S/F
- Switch grass (Panicum virgatum) S/F
- Tickseed (Coreopsis verticillata) S/F
- Turtlehead (Chelone glabra) S/F
- Yarrow (Achillea filipendulina) S/F
Use a handsaw to divide these
- Amsonias (Amsonia spp.) S/F
- Astilbes (Astilbe spp.) S/F
- Bear's breeches (Acanthus spinosus) S/F
- Doll's eyes (Actaea pachypoda) S
- Foxtail lilies (Eremurus spp.) F
- Gayfeather (Liatris spicata) S/F
- Goatsbeard (Aruncus dioicus) S/F
- Joe Pye weed (Eupatorium maculatum) S/F
- Lilyturf (Liriope spicata) S/F
- Male fern (Dryopteris filix-mas) S/F
- Meadowsweets (Filipendula spp.) S/F
- Peonies (Paeonia cvs.) F
- Solomon's seal (Polygonatum odoratum) S/F
- Wild indigo (Baptisia australis) S Divide After Flowering /F
Cut up rhizomes and tubers with a sharp knife
- Arum (Arum italicum) F
- Bergenia (Bergenia cordifolia) S/F
- Caladiums (Caladium spp.) S
- Calla lily (Zantedeschia aethiopica) S
- Cannas (Canna spp.) S
- Corydalis (Corydalis lutea) S/F
- Dahlias (Dahlia cvs.) S
- Elephant ears (Alocasia spp.) S
- Irises (Iris spp.) F
- Lady fern (Athyrium filix-femina) S/F
- Lily-of-the-valley (Convallaria majalis) S/F
- Rhubarb (Rheum palmatum) S
- Rodgersia (Rodgersia pinnata) S/F
- Spurge (Euphorbia griffithii) S/F use gloves
- Wild ginger (Asarum europaeum) S
Don’t divide these perennials.
- Alyssums (Alyssum spp.)
- Candytuft (Iberis sempervirens)
- Carnation (Dianthus caryophyllus)
- Delphinium (Delphinium X elatum)
- Euphorbia (Euphorbia characias ssp. wulfenii)
- Foxgloves (Digitalis spp.)
- Garden sage (Salvia officinalis)
- Geraniums (Pelargonium spp.)
- Lavender cotton (Santolina chamaecy-parissus)
- Lavenders (Lavandula spp.)
- Rose campion (Lychnis coronaria)
- Rosemary (Rosmarinus officinalis)
- Russian sage (Perovskia atriplicifolia)
- Sea hollies (Eryngium spp.)
- Silvermound (Artemisia schmidtiana)
- Sweet pea (Lathyrus latifolius)
- Trillium (Trillium grandiflorum)