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The Great Divide: Perennial Propogation

by dig the dirt editor

Perennial division isn’t just a great way to get more plants--it’s also the best method to keep your perennials in top shape. That’s because most perennials need to be divided every several years in order to bloom to their full potential. For spring- and summer-blooming perennials, autumn is the optimum time to divide.



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Why perennials need a break
Perennials need to be divided just as you need that cup of coffee in the morning--for its rejuvenating effect. Perennials (thanks to your gardening efforts), get bigger and better every year. But they can grow too big and overcrowd other plants. And they can simply get too large for their own good--if you don’t divide some perennials, they’ll stop blooming. For example, when peonies need dividing, they no longer expend energy on producing blooms, although the foliage comes up every year. Other plants, such as lamb’s ears or coreopsis, die in the center, but continue to grow outward. So in order to keep your perennials in top shape, you must divide them.




Lift and separate
The plants that divide best are those perennials that grow in big clumps with fleshy root stocks such as daylilies and peonies. Other good division candidates include tuberous plants, such as irises, and perennials that develop crowns, such as heuchera and ajuga. Here are 10 easy steps to perennial division:


1. Dig area around the plant with a sharp border spade. You are going to sever some roots, so brace yourself. It’s okay--the plant will survive.

2. Gently remove the clump from the ground and set on a drop cloth or hauling bag.

3. Place two forks, back-to-back, in the center of the clump.

4. Pry apart the clump into two pieces.

5. Continue dividing each of the pieces, making sure each division section has a shoot to grow upward and roots to grow downward. (Or you can plant larger divisions, for bigger plants.)

6. Remove any dead or woody parts of the plant. Also, clip back about half of the foliage on the plant so that it doesn’t compete with the root system for growth.

7. Immediately plant the divisions. You can place the mother plant back in the spot she was occupying before the division.

8. Water and foliar fertilize each division well.

9. In areas that receive frost, mulch around the base of the plant with shredded bark or leaves.

10. Continue to water well (to help roots grow strong) until the ground freezes.



Lamb's ear


To divide or not to divide
Once you’ve successfully divided perennials, you’ll be wandering around your garden with forks in hand, looking for more plants to separate. But there are situations when you should not divide:


  • Wait to divide if conditions in your garden have been very dry, which has stressed the plants in your garden.


  • Consider the temperature. If the autumn has turned unusually cold, it’s a good idea to forgo perennial division for the year. In the cold weather, new divisions may not be able to set enough root growth to overwinter.


  • Is your mother plant healthy? If the plant is unhealthy, infested, or stressed, it’s best to wait until the following fall to divide.


  • Can it be divided? If the plant that has just one stem, and hence, one main root, you can’t divide it. Plants such as salvia, butterfly weed, gas plant and lavender should be started from cuttings or seed.


  • Is it blooming? Never divide a plant when it is still in bloom.




Divide plants opposite of their bloom time. Rudbeckia blooms in mid-summer and fall, so the best time to divide these plants is in spring. Peonies bloom in the spring, so divide them in the fall.



perennial propogation, dividing perennials