·        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)