When it's time for plants to part ways

If perennials and bulbs look crowded, dividing will do them good

In The Garden

October 12, 2003|By Megan Sexton | Megan Sexton,Knight Ridder / Tribune

It's always near the top of any list of fall gardening chores: divide perennials.

Why? Large clumping plants -- Such as cannas, black-eyed Susans and day lilies -- end up competing with one another and other things in the garden, meaning fewer blooms.

Plus, when there's more room between plants, there's better air flow -- and less chance for disease to spread.

An added benefit? Dividing perennials gives you more plants to share with friends and neighbors.

Why in the fall? Because plants tend to transplant better when the weather is cool. They'll get stressed any time you transplant them, but doing it when it's too hot or too cold can be too tough for them. Transplanting in the fall gives the plants time for their roots to grow before the winter sets in.

How often? It depends on the plant. Think about dividing them when they start to look crowded, or start infringing on other plants in the garden, or start to die off in the middle.

As a rule of thumb, every two to three years is a good schedule to divide most perennials.

Exactly what does "divide" mean?

Once you remove the plant and its roots from the soil, it's time to divide it. You can do that several ways, depending on the type of plant you're working with. A day lily's roots often are tangled, so you can use a garden fork to pull the roots apart and break them into separate plants. Hibiscus can be cut with a flat-blade shovel.

With bulbs, you need to be sure to dig deep enough so you don't damage the basal plate, the area at the bottom of the bulb that holds the scales together and produces roots. You can divide one bulb into as many pieces as you like as long as you have a piece of the basal plate on each. Some people use scissors, knives, shovels or simply their hands to pull apart the roots and divide the perennials.

The next step is to cut off the old flower stalk, making it easier to handle. Doing that also compensates the plant for losing some of its roots, meaning that the stress of transplanting will be eased.

"A lot of plants can go into transplant shock," said Andy Cabe, curator at Riverbanks Zoo and Garden in Columbia, S.C. "If you cut the foliage and if you [divide the plants] at the right time of year, you can reduce the amount of transplant shock."

Once the plants are out of the ground, it's time to think about what to do with them. Bulbs, or any plants with large storage roots, can sit awhile in a cool, dry place. Other plants, such as black-eyed Susans, should be put back in the ground as soon as possible, watered and given a fresh covering of mulch.

Most plants should be put back in the soil at the same depth they originally were planted. An exception with bulbs: Sometimes as they grow and need to be divided, they'll push up toward the surface. Make sure you plant the bulbs a little deeper than they were when you dug them up.

It's important with perennials to keep on top of the dividing chore. It's harder to divide them when they've encroached into another plant species.

The most important thing to remember when you're dividing plants?

"Don't forget about it after you divide it," Cabe said. The plant has been disturbed. Make sure you water it well when you get it back in the ground and put some mulch over the top.

"Make sure it gets a little extra care," he said.

Will all the new plants survive?

If it has enough roots, it should live, he said. "But inevitably, you're going to lose something."

Fall chores

The cooler weather is a perfect time to be in the garden. And there's plenty to do. Here are some of the chores for the fall garden:

* Prepare beds / areas for shrubs and trees so they are ready for new plants.

* Plant container-grown and balled and burlapped trees and shrubs, including those that flower in the spring. Transplant shrubs.

* Clean up the remains of annuals and perennials to discourage disease and insects in next year's garden.

* Put out plant markers while perennial foliage is still evident.

* Dig up tender summer bulbs such as caladiums, dahlias, gladiolas and elephant ear. Dry for a week, then store them in peat moss for the winter.

* Check for diseased and damaged tree limbs and remove them. But hold off on any significant pruning. Pruning stimulates the growth of plants, and the new growth will be susceptible to cold damage.

* Plant annuals for fall / winter color, such as pansy, ornamental cabbage and kale.

* Plant perennials for fall / winter color (sedum, chrysanthemum, aster and many others). Fall is a perfect time to plant ornamental grasses and spring-blooming perennials, too, giving them time to establish strong root systems.

* Check plants that will be coming indoors for the winter for repotting, pruning and insect control.

* Discontinue feeding the fish in your water garden when the water temperature drops below 55 degrees.

* Mulch with organic materials (pine straw, bark, compost).

* Attract migrating birds to your home by keeping your bird feeders well stocked and the bird bath filled with fresh water.

* Pick up fallen leaves. After all of the leaves have fallen from your rose bushes, remove the mulch, and replace it with fresh organic matter.

* Rake up debris from around your fruit trees. Removing spent leaves and rotten fruit from underneath the tree will help to prevent disease from spreading to next year's crop.

Sources: Clemson Extension Service; Midlands Master Gardeners 2003 calendar; Andy Cabe, curator at Riverbanks Zoo and Garden, Columbia, S.C.

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