Evaluate perennials now for next growing season

By Pam Corle-Bennett, Contributing Writer 4:54 PM Friday, August 20, 2010

This is a good time of the growing season to evaluate your perennial garden and determine what you might want to purchase for next year to fill in or what plants could benefit from being divided.

Dividing perennials serves several purposes. First, it’s a good way to control plants that have outgrown their location. Second, it’s a way to renovate or rejuvenate perennials that have begun to decline or have lost vigor and bloom. And finally, it’s a wonderful way to share plants with fellow gardeners.

There are different schools of thought on how often perennial plants should be divided. Some like to divide perennials when they still look good, before they look bad. Others wait until they are in really bad shape before dividing.

I like to stick in the middle — I divide most perennials when they just start to look like they are a little tired.

Some signs of this include clumps that begin to develop open or dead spots in the middle of the plant, blooms that aren’t are as heavy or vigorous, or the plant just didn’t do as well as it has in the past.

There are some perennials that benefit from a regular dividing schedule. For instance, daylilies look much better in the garden when divided every 2-3 years.

Other perennials such as bleeding hearts and peonies don’t like to be divided once established.

The best recommendation is to research the plant and determine what it prefers.

The best time of the year to divide is normally the season opposite of the bloom.

The main reason for doing this is for the bloom. If you divide spring blooming perennials this time of the year, they are more likely to bloom and look pretty good next season.

Make plans for dividing now and wait until we get past these next few weeks of potential hot weather. However, don’t wait too long or go too late into the fall.

It is important that you do it early enough that the roots have an opportunity to develop prior to cooler temperatures.

This is also true for planting any new perennials in the fall. The later you go in the fall, the greater the likelihood of the plants heaving in the winter. If you can’t avoid a late planting or dividing and transplanting, mulch the plants heavily in the later fall in order to prevent soil heaving.

Make notes from this growing season. Were there periods of time that were missing color throughout the summer? Did you have more blooms during the mid-summer and not enough in the spring or fall?

This is a great time to write down your notes and make plans for next season’s perennial garden.

I already have one note in my garden calendar for next spring: Use pre-emergent herbicide and mulch early next season! It seems like all I have been doing in the perennial border lately is weeding.

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