Perennials may be overcrowded

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By Dennis Morgeson

Have your perennials been in their current location for at least three years?  Have you watered and fertilized them regularly throughout the growing season, yet they haven’t bloomed as much as usual and they just look tired?  Your perennials may be over crowded.  
As a general rule, perennials that bloom in the spring, such as peonies, should be divided in the fall; however, daylilies and iris should be divided now, and perennials that bloom in the summer and fall, such as chrysanthemums, hostas, and asters, should be divided in the spring.  It is best to divide perennials just as they are entering dormancy (after a hard frost) or before they break dormancy (when new growth begins) in the spring.
When you decide to divide your perennials, dig around them with a shovel or garden fork to allow the plant to be lifted with a good portion of its root system in contact.  Shake or work the root ball with your fingers to dislodge as much soil as possible.  The newest plant growth will be around the outside of the clump.  Trim the tops of the plants to 2-3 inches and remove any broken or very long roots (generally you want a larger root system than top growth).  Next, pull or cut the clump apart leaving new and old growth on each section; a perennial clump that is 10”-15” wide can make several new plants, however I like to cut them into four pieces.  This allows you to still have mature plants in your garden.
After planting your new perennials, apply a layer of mulch and keep them well watered for several weeks.  Don’t fertilize until new growth begins in the spring. It may take your new plants a season or two to return to their full potential, however if you only cut your clump down by 1/2,  you will probably have a nice show next year.
Remember, if you have too many perennials to plant after you divide them, there is always a gardener out there to share them with.