<a href="mailto:askMG@cornell.edu">By AMY IVY</a>
Cornell Cooperative Extension
April 21, 2008 04:53 am
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One of my favorite things about perennial flower gardening is watching the garden come back to life each spring. Without lifting a finger, I can sit back and watch my garden fill first with green shoots then all kinds of flowers, one after another.
Well, I may not have to lift my finger right now, but I sure have done plenty of finger lifting over the years to get my garden where it is! And I'll have lots to do once the weeds emerge along with my daffodils and tulips. But still, it's fun to be able to sit still for now and watch things emerge.
Once those first shoots emerge, it's time to consider which ones need dividing. It's odd, but chopping up your beloved perennials actually invigorates them. You'll have stronger plants with more blooms if you chop them up every few years.
This doesn't apply to all perennials, but it does to most of them. My Shasta daisies do much better if I dig up their clumps every year and replant only the strongest sections. But for most, three years is a reasonable time span.
Some of the exceptions, the ones that do not like being divided at all, are peonies, baptisias and oriental poppies.
EXPANDING CLUMPS
All perennials grow larger over time, some faster than others. The most common way perennials expand is by sending up additional shoots from their base. A single clump of yarrow, for example, may be just four inches across when planted one spring, but after a couple of years that clump can have grown to 12 or 14 inches in diameter.
As these clump-forming perennials grow, the newest and most vigorous growth is around the outside of the clump, and the center growth becomes overcrowded and weak. This is commonly called the "doughnut effect." The center of this "doughnut" is weak, unproductive and prone to problems.
To divide a typical clump-forming perennial, simply use a round-pointed shovel and slice through the plant, cutting the top growth and root ball in half. These sections can be further cut into smaller divisions depending on the size of the original plant. An ideal size for a division is four to six inches in diameter. Each of these divisions can be replanted, but be sure to leave enough room between them to allow each to grow into a full-sized plant.
When replanting any divisions, prepare the planting hole first by mixing in some well-rotted manure, compost or peat moss. Water the new divisions regularly until they become established.
Wait to divide your spring-blooming perennials until just after they bloom or else you may not get any bloom this year. This group includes dianthus and bearded iris. Bearded iris grow from thick rhizomes, that you need to cut apart when dividing, a little different from most other perennials. Summer and fall blooming perennials can be divided in May and should flower nicely later this year.
WELCOME, ANNE!
Last week on this page there was an article announcing our new horticulture educator, Anne Lenox Barlow. Starting next week, Anne and I will take turns writing this column. I have a administrative duties I must tend to as executive director, and Anne will be the primary contact person for the gardening public. When you call our office, you'll be directed to Anne or our Master Gardener volunteers.
I think you'll enjoy a fresh perspective. Anne has been on the job almost a month now and is a terrific fit for us. Our varied staff has already begun thinking of programs we can do to involve gardening, the environment, healthy eating, local agriculture, youth and healthy living.
It's an exciting time here at Cornell Cooperative Extension. I urge you to keep in touch with us. Our newsletter, North Country Gardening, is available at no cost to Clinton County residents ($15 for out of county) and our revamped Web site showcases all of our various program and events plus back issues of our newsletter. Check it out at www.cce.cornell.edu/clinton
I'll still keep my hand in somewhat, especially with the commercial turf and landscapers, but otherwise I'll be in the background, supporting Anne and our Master Gardener volunteers. Please join me in welcoming Anne. Her position is full time, so she'll be here Monday through Friday to provide more continuity. I'm thrilled to have her on board!
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