Growing Concerns 510: Dividing perennials, emerald ash borer control and wood disposal

 Early Spring!

Time to divide crowded perennials and those that no longer flower well

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Dear Janet,

I'm starting to divide my perennials - wow, how they grow. Do I throw out the center of the sedum when I divide it?

I'm digging up perennials that have gotten too big and splitting them into smaller pieces but I wonder if there are others I should divide even earlier to keep them in the best shape.


Dear M.G.,

Perennials bloom best and are most resistant to disease and insect problems when they are not crowded. So it's a good idea to divide whenever a plant reaches the maximum size your garden allows.

Although you can divide whenever you have the time to do it, April is an excellent time for this job, and so is September. At those times we can be fairly certain that replanted pieces will have at least a month of cool air and warm soil, perfect conditions for establishing new roots.

As a general rule, divide perennials with running roots every two years, and throw out the oldest, center parts. Bee balm, some artemisias and yarrows are in this group.

Divide any clump--forming perennial such as tall sedum 'Autumn Joy' when you see it is producing smaller stems at its center than on the edges. Those central, crowded stems bear fewer, smaller flowers, are more susceptible to pest problems and often need help standing up. Take a look at your hostas, daylilies, Siberian irises and ornamental grasses now as new growth starts and you will see that even those still in tight clumps need division to free up the central stems.

Divide every plant you lift into at least four pieces. Break off the oldest, center bit of each piece and compost it. Re-set only one division in the original space. Give the rest to friends, start new gardens with them, or put them on the compost.

Short reports:

Check around for disposal sites for emerald ash-borer infested wood.

Be sure to call around locally to look for a site to dispose of emerald ash-borer infested wood.  These infested trees should not leave your local area.  Search on line to get ideas of places close to you.  If you wish to dispose of them yourself then find a professional to talk you through the steps to be sure that the infested would does not contribte to harming other trees.

"For shame!" To those tree care companies...

...who are trying to cash in on the concern of ash tree owners by claiming to have an "Emerald Ash Borer Solution." Although such companies can defend their ads as true because their treatments involve a water-soluble insecticide as a possible preventive to EAB infestation, it is most certainly not a cure for already infested trees or an answer to the problem as a whole.

If those companies are the experts they claim to be and someone you should work with on your trees, they will honestly admit at least three things:

- That there is no saving an ash tree already showing significant damage.

- That insecticides cannot reach borers already inside an ash tree.

- That insecticide treatments aimed at keeping the borers out of a tree not yet infested cannot be guaranteed and must be repeated every year.

If they are thinking of the long term interests of their clients within the six-county EAB quarantine area they will recommend that you remove infested ash trees as soon as possible. They will also urge their clients to start thinking about planting replacement trees near still-healthy ashes, because they have heard and understood Forestry Department, DNR and Department of Agriculture experts who project that every ash tree within that area will probably become infested during the next three years.


Green thumbs up

to more than 120 volunteers who have spent three days learning about ash trees and emerald ash borers, and being tested to become EAB Town Crier and Scouts. They did all this so they can volunteer many more days over the next two years to walk their communities and provide information directly to ash tree owners. I am so proud to be working with all of you!


Green thumbs down

to those who use the words "done" and "garden" in the same sentence, as in "When will this garden of yours be done?" You don't understand the concept, because a garden is never "done." It is a living, changing thing and all the more beautiful because of those characteristics. Those in the know, like W.S.  say, "A garden is a process, not a product, and I intend to keep on growing all my life!"


Originally published 4/5/03




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