Dividing Perennials Keeps Them Healthy
Dividing perennials is an easy way to rejuvenate plants and also provide more plants for the garden. The onset of cooler weather means that it’s the perfect time to divide certain plants.
As a rule of thumb, spring and summer blooming perennials should be divided in the fall, and fall blooming perennials should be divided in the spring.
Most perennials need to be divided every three to five years. Chrysanthemums and asters may need to be divided more often. Signs that perennials need to be divided include smaller than normal flowers and centers of clumps that are dead or hollow. If plants are growing and flowering well, they should be left alone.
If you’re going to divide perennials, avoid doing it on hot, sunny days. The best days for dividing are cool, cloudy days when the plants have a reduced risk of drying out.
Water plants well a couple days before dividing, and prepare the area where the divisions will be planted in advance. Stems can be cut back to six inches above the ground before digging begins, which will make moving the plants easier and reduce water loss from the plant.
Use a sharp pointed shovel or fork to dig down deep on all four sides of the plant. Then put your shovel underneath the clump and pry upward to remove the plant. If the clump is too large or heavy, it can be cut in sections before being lifted from the ground.
Once you have the clump out of the ground, division depends on the type of root system that the plant has.
Many common perennials have spreading root systems, which have numerous slender matted roots with no distinct pattern. These include bee balm, asters, lambs ear, and coneflowers. Dividing these perennials can be as easy as pulling apart by hand or cutting with shears or a knife. Strive to maintain three to five vigorous shoots per division.
Other plants, like hostas, daylilies, and ornamental grasses, have clumping root systems in which roots originate from a thick, fleshy center. Dividing these types of plants often requires slicing through the center with a sharp knife. At least one developing eye or bud is needed per division.
Overgrown plants are often difficult to divide and may require forceful separation with two forks placed back to back. In extreme cases, a saw or ax may be needed.
Dividing plants gives you the opportunity to clean up any dead or dying plant material. Inspect the plant before you plant it, taking care to remove any broken roots.
Divisions should be planted at the same depth as they were originally planted and watered well after moving. Doing a little division now will rejuvenate the garden and keep plants performing as expected.