By Ellen Barcel
One of the nice benefits of growing perennials is that they come back year after year without replanting — it saves time, energy and money. However, as the years go by, perennial beds can become overgrown and need to have their plants divided.
When is the ideal time to divide your perennials? Perennials can be divided almost any time, but, ideally, don’t divide perennials in the summer since it will be harder to keep the new plants growing with the heat and lessened rain. In an emergency, for example, when having to clear part of your property for new construction, divide as needed even if it is 90 degrees outside. But this is an emergency situation rather than good planning and means you need to take extra care to keep the plants thriving.
The rule of thumb is to divide spring and summer bloomers in the fall. That means that you should have already divided plants like hostas. Fall-blooming plants (like mums, asters, Montauk daisies, etc.) should be divided in spring. By dividing them at the appropriate time, more of the plant’s energy will go into growing new roots and leaves. However, always do some research on the specific plants you need to divide before digging up the perennial clump as some plant species can be very persnickety when it comes to dividing time. And, some plants, like black-eyed Susans and coneflowers can be divided in either spring or fall.
Some perennials need to be divided every three or four years, depending on how thickly they have grown. Others don’t need to be divided for many years, like peonies. If there were fewer flowers last year than in the past, it’s a sign the clump needs to be divided. If there is a bare spot in the center of the clump, that, too is a sign the perennials need to be divided.
Steps to follow:
• Look at the size of the clump and decide into how many pieces you want to divide the clump.
• If possible, dig the appropriate number of receiving holes before you actually cut the clump. This will lessen transplant shock. You can, naturally put one of the divisions back into the original hole.
• If you can’t plant the divisions immediately, wrap them in newspaper or burlap, dampen with water and store in a bucket in a cool, shady place. Plant them ASAP.
• It’s easiest to dig up and divide a clump of perennials after there has been a rainfall.
• Start digging at the drip line and work your way around the outside of the clump of perennials.
• Once you’ve lifted the clump, if possible, divide the rooted sections by hand. This will lessen root damage.
• If necessary, take a sharp spade or gardening knife (make sure you have thoroughly cleaned it first) and cut the clump into several sections, making sure that you have roots attached to each section.
• If there was a bare spot in the center of the original bed, do not replant that section, but rather discard it to your compost pile. • Make sure you add organic matter to the newly planted divisions of the perennials.
• Keep the new plants moist, but not soggy, until they have had time to establish themselves. Mulch would be useful here. In a few months, your new plants should be growing well.
Ellen Barcel is a freelance writer and master gardener. To reach Cornell Cooperative Extension and its Master Gardener program, call 631-727-7850.