If you have a perennial flower bed, you know what a joy it can be to see all your favorites in full-bloom during the course of the growing season. It’s hard to top the gorgeous, fragrant beauty of peonies in the early summer, the delicate, feathery blooms of Astilbe or the palettes of leaf colors and textures of literally hundreds of Coral Bells (Heucheras).

In your perennial garden, at times you’ve probably also noticed that some of these plants simply grow themselves into non-flowering clumps of leaves or worse, simply crowd themselves out. Plants like Black Eyed Susan (Rudbeckia), Daylilies (Hemerocallis) and Irises really depend upon division for their flowering survival. If they are not dug and divided every few years, they stop flowering.

 

WHEN TO DIVIDE YOUR PERENNIALS:

Most perennial plants benefit from periodic division. Dividing perennials doesn’t have to be intimidating. Plants really are very resilient and very forgiving. In general, perennials can be divided at any time. However, unless the plants are in “imminent danger”, it’s best to follow this rule: If the plant blooms in the Spring, it should be divided in the Fall. If it blooms in the Summer or Fall, it should be divided in the Spring.

It’s best to divide perennials during spring or fall because the air temperatures tend to be cooler, while the soil temperatures are warm and stimulate rooting of new transplants. This minimizes transplant shock and your perennials will become established much more quickly. Cooler air temperatures help protect the plants from the effects of drying sun and wind.

 

ROOT SYSTEMS:

Perennial plants have different types of root systems and almost all transplant very well. Taprooted plants such as Poppies (Papaver), Butterfly Milkweed (Asclepias) and False Indigo (Baptisia) are the exception. Taproots are very fleshy, long roots that extend deep into the soil. Rhizomatous rooted plants are those that have their roots at or just below the soil surface and some can be aggressive in nature. These type of perennials usually divide and transplant pretty well. Fibrous rooted plants or those with many, many smaller roots that extend to various levels within the top layers of the soil, handle transplanting the best.

 

WHY TO DIVIDE YOUR PERENNIALS:

Division of perennials is done for essentially four reasons then:

It keeps your plants BEAUTIFUL: Division can rejuvenate the clump, giving the plants room to grow and flourish.

It keeps your plants HEALTHY: Perennials that are overcrowded, stunted in growth and/or otherwise stressed are more prone to insect and disease issues. Keeping them divided reduces stress on the plant, allowing it strength to ward off pests.

It keeps your plants WELL-BEHAVED: No one likes a bully, right? Division of your perennials keeps everyone in their “personal space”, especially the rhizomatous, aggressive types.

It keeps your plants MULTIPLYING: Every time you divide a plant, you make more! You can use those in other areas of your own garden or give them away to friends and family.

 

HOW TO DIVIDE YOUR PERENNIALS:

You will want a sharp shovel because this task is made easier with the proper equipment. Starting at what would be the “drip line” of the plant, cut a trench around the plant you would like to dig and divide. Cleanly sever the roots around the entire plant, cutting down at an angle under the plant, so it can be lifted from the hole. One piece of advice is to water the clump a couple of days before you are going to try to dig and divide it. This loosens the soil and makes this task a bit easier.

If you are dividing plants in the spring, there shouldn’t be much green top-growth to worry about. Try to do it early enough so that is the case. However, if you are trying to divide a plant in the summer and have a lot of green foliage to deal with, consider tying the foliage together before attempting to dig it out. In the fall, you can cut back all the top growth before digging the trench. This will make it a much easier task.

Once you have the clump loosened with the shovel, gently lift the clump from the hole. Try to leave the clump intact as much as possible. Shake and wash the excess soil from the clump. Once this is done, you want to gently pull apart each crown, remembering that you will need leaves (or buds) and roots on each plant in order to re-plant this into the ground. In order to get the clump apart, you may have to cut it with a knife. That’s okay! Use a sharp knife and cut the clump into sections, again making sure you have leaves (or buds) and roots for each part you want to re-plant. This is over-simplified and there are some exceptions, but this applies as a general rule.

Replant your new divisions as soon as possible to prevent them from drying out. Take care to plant the new plants at the same depth they were growing. Planting too deep may prevent flowering or loss of the plant. Water them well and cover with mulch to prevent them from desiccation. Monitor them for moisture and make sure they receive adequate water while they are becoming as big, bold and beautiful as their parent plants!

 

SOME SUGGESTIONS:

Perennials That Do Not Like To Be Disturbed:

Besides Poppies (Papaver), Butterfly Milkweed (Asclepias) and False Indigo (Baptisia)

  • Bleeding Heart (Dicentra)
  • Lenten Rose (Helleborus)
  • Lavender (Lavendula)

 

Divide Every 2-3 Years:

  • Asters
  • Yarrow (Achillea)
  • Blanket Flower (Gaillardia)
  • Coreopsis

 

Divide Every 3-4 Years:

  • Hosta
  • Astilbe
  • Daylily (Hemerocallis)
  • Beebalm (Monarda)
  • Peony (Paeonia)
  • Phlox
  • Purple Coneflower (Echinacea)

 

There’s something very rewarding about dividing perennials. Just digging in the soil and knowing that your garden beauties are getting a new lease on life is very satisfying. We’re here to help make your perennial garden a success. Please call us and we’d be happy to answer any questions you have about dividing specific perennials.