How do you know it needs to be divided?
-Not flowering as well as in the past
-Bare spots in the center of the plant
-“Floppy” (many stems are laying on the ground)
-It has spread and become invasive
*Most perennials benefit from division every 3-5 years*
As a general rule (that is often broken!!)-
Divide Spring flowering perennials in the Fall,
and later flowering perennials in the Spring.
How to Divide Perennials:
-Can be done any time but Spring and Fall are best
-Water the plants the day before you plan to divide them.
-Try to do it on a cloudy day- if this is not possible at least wait until the heat of the day is over.
-Dig the clump out (go out as wide as you can)
* Some perennials don’t need to be totally dug up to be divided- sometimes you can carefully dig up the small side shoots (geraniums, Jacob’s Ladder, etc.).*
-Try to keep the roots intact
-Shake, wash, or brush off excess soil
-Pull apart individual crowns into smaller clumps.
Be careful- each clump needs roots and leaves to survive!
-Replant at the same depth.
-Mulch to help keep moist and cool while they are becoming established.
Perennials that you may not want to divide:
Artemesia, Baptisia, Bleeding Heart, Butterfly Weed, Hellebore, Lavender, Poppies, Peonies (although these can be divided in the Fall if need be).
Plants NOT to cut back in the Fall:
Artemesia, Asters, Astilbe, Balloon Flower, Basket-of-Gold, Bergenia, Black-eyed Susan, Bleeding Heart (Fern Leaf), Blue Mist Shrub, Butterfly Bush, Butterfly Weed, Campanula, Cardinal Flower, Coral Bells, Cushion Spurge, Delphinium, Dianthus, Foam Flower, Foxglove, Gayfeather, Geum, Globe Thistle, Grasses, Hosta, Italian Bugloss, Joe-Pye Weed, Lady’s Mantle, Lamb’s Ear, Lavender, Lupine, Mums, Oriental Poppy, Pincushion Flower, Purple Coneflower, Red Hot Poker, Russian Sage, Sedum, Tickseed, Turtlehead, Valerian
(For the reason see the link on our Winterizing Your Garden Page under Perennials).