After several years of being in one spot some perennials tend to decline, as they get overcrowded and exhaust the soil. Dividing them and putting them in fresh soil with compost and worm castings, rejuvenates them so they will grow and bloom better. Tools: Hori Hori Knife, axe or sharp spade. For a ‘hands-on’ demonstration of the many techniques for dividing – register to join the free workshop at Plant Paradise Country Gardens: Dividing Perennials
When to do the Job?
1. Divide plants when they are not flowering or getting ready to flower.
2. Divide when new leaves are just emerging.
3. Allow at least six weeks before the ground freezes.
4. Cloudy day, preferably before a rainfall.
5. Spring and early summer blooming perennials are best divided after they finish blooming.
6. Fall blooming perennials are divided in the spring.
For bulbs like Daffodils, Tulips, Alliums, Lilies, Muscari, Crocosmia etc…divide after flowering when the leaves start to turn yellow. Dig all the way around the edge of the clump to loosen the soil, sticking in your shovel as deep as possible. Then slide underneath and lift the whole clump. When you get the clump out, grab it by its leaves and shake off the soil. Simple pick them apart. Leave the roots attached to the bulb and replant right away and water them in.
Dividing Clumps of Rosettes
For rosettes of Primula, Geraniums, Columbine, lungwort, Heuchera, Sedum and clump forming ferns such as Japanese Painted ferns…etc. dig all around the clump, a few inches beyond the edge of the leaves, and dig it out the ground. Shake or wash away the soil. Starting at the edge of the clump, pinch a rosette firmly where its leaves and roots come together. Usually you can snap it off, but you may require a knife to sever the connection. When the clump is very dense it is best to use a sharp knife. Divide the clump into sizable pieces. Replant promptly and water.
Dividing Mats and Patches
Patch forming mats of Yarrow, Rudbeckia, Echinacea, Monarda, Ligularia, sweet woodruff, Epimedium, etc… Divide in early spring. To divide an entire patch into several new sizable plants, dig it out and lift as a whole or in sections, place on the ground or a tarp and divide into big individual pieces with a sharp spade or knife. Replant and water.
Dividing Tough Clumps
For tough clumps of Daylilies, Astilbe, Veronicastrum, Joe-pye weed, Heliopsis, Salvia, and ornamental grasses etc… Identify where the growth comes out of the ground and dig a circle of at least 2 times as wide around the edge. Pry underneath with your shovel and lift the whole clump out. Hose off the soil. To divide use a very sharp saw, knife or very sharp spade or axe. You will encounter woody or gnarled knots, just keep cutting. Replant and make sure the top of the crown is level with the soil. It is best to plant a little high in fresh soil as the large and heavy clump will sink.