Propagation by Division
Reproducing plants by division is a propagation technique used for landscape plants that have multiple stems or crowns. Many plants have just a single stem growing from the ground and therefore, cannot be propagated using this method. However, there are many plants that have groups of stems emerging from the ground that can easily be divided into new plants.
Just a few species of plants that are easily divided include Chrysanthemums, Hostas, Ornamental Grasses, and lots of different perennial flowers.
Division works exactly like it sounds. You basically just dig up the “mother” plant that you intend to divide and quite simply split it apart into two or more plants. The larger the parent plant, the more times you can divide it.
If your goal is to simply produce new plants without shrinking the size of the parent plant, then ideally you would only take a few divisions from the edges of the source plant. In many cases, you can do this without having to actually remove the parent from the soil. Using this example, just clear the ground around the base of the plant so you can identify which sections of the parent plant you would like to divide. Then take a pointed spade and bury it into the ground between the host plant and the division you would like to remove. Make three additional spade cuts around the part you are removing, making sure to completely sever the division from the parent plant while cutting all the roots that are securing it in the ground. Using the spade, just lift the divided section out of the ground. Now all you have to do is trim the roots a bit if they need it and replant the division in a new location.
The other option, if you don’t mind slimming the size of the parent plant, is to completely divide the parent plant into small, equal size plant divisions.
Propagating by division is best accomplished in early spring, or in the late fall will usually work as well. For the best results, propagating plants by division should be done during the dormant cycle of the plant, or when the plant is about to break dormancy in the early spring.
Dormancy season typically begins in the fall after your first hard freeze, not necessarily after a frost. In most cases, frost is usually not severe enough to trigger dormancy in perennial plants. A good hard freeze occurs when the outdoor temperature drops below 32 degrees Fahrenheit for at least a few hours time. After a hard freeze has taken place, any remaining leaves on trees will be dry, damaged, and fall to the ground the next day due to severe cold damage.
Once dormancy begins, plants will remain dormant until the spring and the temps begin to rise. As the temperature increases, plants become active and new growth and leaves will begin to appear. Root activity occurs anytime the soil temperature rises above 45 degrees F. throughout the winter, yet the plants do not officially emerge from their dormant period until new leaves begin to appear.
Nursery operations can only dig deciduous plants during their dormant stage. Once the deciduous plant produces leaves in the spring, it is not safe to transplant until late fall after it has gone dormant again. Disturbing a deciduous plant once it leafs out in the spring will immediately put the plant into shock, and in many cases, kill it outright.
Evergreens are a bit of a different story. They cannot be safely transplanted once new growth has begun in the spring. Once the new growth hardens off later in the summer, it is safe to transplant them. Of course, even with evergreens, transplanting during the dormant period is usually the best bet.
Getting back to the topic of division, basically, all that is required to completely divide a plant is to dig up the parent plant. The entire plant and root system should come out of the ground in one large clump. Just put the entire plant on a hard surface and cut the root system into several pieces using a large knife or spade, depending on the size of the plant. Ideally, each division will have two or three sprouts, or eyes. Of course, determining this is much easier in the early spring when eyes have begun to show, but leaves have not.
Once you have made your divisions, you simply replant each individual division back into your garden. Keep these divisions watered, but not soaking until they have reestablished themselves.
Division is probably the simplist form of plant propagation, but it is unfortunately only effective with a relatively small number of plants. Division generally will not work on what are considered the higher forms of landscape plants. Unfortunately, if a plant has but a single stem emerging from the ground, it must be propagated using another method.