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Dividing your perennials will pay dividends

Published 4:55 pm, Thursday, May 8, 2014
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Now is the absolute best time to divide certain perennials, more precisely those that bloom after July 4. Try doing them this early in their seasonal life cycle; they won't even know you bothered them.

A perennial comes back every year, resulting in a long life that requires us to periodically divide them to keep them young and spry. The best part: They'll let you know when that time has come; their flowering diminishes in quantity and size, for many their crown will resemble a doughnut with a dead, brown portion in the middle, stems will become weaker and as a result topple over due to lack of strength, or the plant itself will simply run out of "umpff" and return one year at half its original size. All of these are telltale signs that division is needed.

Basically, if a perennial flowers late summer to fall, those are the plants we divide now. Those that bloom spring through early summer, hold off and divide in the early fall. If this is confusing, here's how you can remember who and when so it makes perfect sense.

When we divide, no matter how gently, we are destined to damage some roots, crown or top growth. For the plant to repair this damage, a great deal of energy is required on the plant's part. Perennials that flower early in the season have already dedicated their reserve energy to forming the flower, leaving little left for repairs if we divide them now.

However, the opposite is true for late-blooming perennials. Since their flower buds have not been formed, most of their energy is available, should a repair be necessary, making them the perfect candidate for division now.

Rejuvenating is the primary reason for division, but others include it outgrew its location, you decide to relocate it to a more suitable spot or the best reason of all: to share your collection with friends.

Since we now know when we divide is based on bloom time, get that journal out and make notes of what you want to divide or move, so when the proper time comes around you are reminded. Should a telltale sign not be apparent at the time you relocate, consider dividing anyway. I do, and its saves a step down the road.

Now, we can only divide those perennials that produce a multiple crown, such as daisies, asters, sedum and Rudbeckias. Perennials such as lavender and Russian Sage are propagated differently, and that's a whole chat for another day.

Some tips when dividing: Prior to digging, thoroughly wet the soil. Dig the entire plant out and then divide. The exceptions are massive clumps of daylily and Siberian Iris; they can become very heavy and impossible to lift whole. For these, cut down through the crown with the shovel and try digging in halves. If still too large, quarter the crown and then lift. I find a bow saw works wonders to divide these crowns once out of the ground.

For "doughnut hole" centers, separate the healthy plants from around the edge and discard the dead center. Perennials whose crown/root have "eyes" or nubs protruding (peonies) divide leaving 5 to 7 "eyes" per clump. When dividing a plant such as a Shasta daisy, the crown will consist of multiple small plants. Again, leave 5 to 7 conjoined and replant. In doing so, the "new" plant will return sizable the next season.

When dividing now, do not cut foliage back, as the plant needs it for the summer; however, when dividing in the fall, cut back to ground level for winter garden sanitation practices. Plant, keep watered and enjoy.

Contact Nancy O'Donnell by e-mail at dodonnell@nycap.rr.com. Gardener's Notebook can be found at http://timesunion.com/life.

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