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Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

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Wednesday - March 18, 2009

From: Newburgh, NY
Region: Northeast
Topic: Pruning, Seasonal Tasks, Herbs/Forbs
Title: Cutting back achillea in New York
Answered by: Barbara Medford

QUESTION:

Last summer I planted three gorgeous hearty achillea with flat, yellow tops, about 3 feet high or more each, in my sunny garden. But after they were done flowering, I left those very pretty brown stems and heads right where they were. It's still cold up here in upstate New York. Should I cut them back and if so, how far?

ANSWER:

You can certainly cut back the perennial Achillea millefolium (common yarrow) in the fall or early spring. It was a good idea to leave the stalks and heads where they could add some interest to the winter garden. Care of most herbaceous perennials suggests cutting back the stalk after it dies back, and cleaning up the area around the plants to prevent mold, insects overwintering and disease. We like to leave about a 6-inch stalk when we trim back perennials to mark their place so, when the first leaves start coming up from the roots, you will not think it's a weed and pull it out. The yarrow in our Image Gallery are all white, but we found this Magnolia Gardens website with a picture of the "Moonshine" cultivar in yellow. 

 

From the Image Gallery


Common yarrow
Achillea millefolium

Common yarrow
Achillea millefolium

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