Plants can be propagated by several different methods. Some depend on the type of plant, others can be propagated by most or any method. It never hurts to try more than one version of the methods below:
Division: It's a simple math concept ~ divide to multiply!
Lift the Parent Plant
Use a sharp pointed spade or spading fork to dig down deep on all four sides of the plant, about 4 to 6 inches away from the plant. Pry underneath with your tool and lift the whole clump to be divided. If the plant is very large and heavy, you may need to cut it into several pieces in place with your shovel before lifting it.
Separate the Plant
Shake or hose off loose soil and remove dead leaves and stems. This will help loosen tangled root balls and make it easier to see what you are doing.
Perennials have several different types of root systems. Each root system needs to be treated a bit differently. The UnRipe Gardener's Journal goes into more detail.
General Guidelines for Division:
In general, divide plants when they are not flowering, so that the plant’s energy can go to root and leaf growth. Divide spring and summer blooming perennials in fall, and fall bloomers in spring.
If you divide in the spring, allow enough time for roots to settle in before hot weather. Spring division is ideally done in the early spring as soon as the growing tips of the plant have emerged. Spring divided perennials will bloom a little later than usual the first year.
Fall division should take place at least four to six weeks before the ground freezes for the plants to become established.
It's best not to divide perennials on hot, sunny days. Cloudy days are ideal, with several days of light rain in the forecast.
Water plants to be divided thoroughly a day or two before you plan to divide them, so that the ground is soft, but not heavy. Prepare the area that you plan to put your new divisions in before you begin to dig the parent plant.
It's often good to prune the stems and foliage to 6 inches from the ground in order to ease division and to force new growth.
Cuttings:
Many plants can be cloned simply by cutting off a piece with three
leaves or more and placing the cutting in a contain of water. It will either work or it won't so it's also the simplest way to make more plants.
Leaf:
Many leaves can be placed stem-end down or edgeways into soil and they will root.
Layering:
This works especially well for shrubs but also works well for many plants with low branches. Dig a shallow trench and press a brand into the soil, and then anchor with a rock of other method so that it stays below the soil surface. In a few weeks roots will appear. Then cut off the rooted section and replant.
Grafting:
This is the common technique in the orchard business. It's a way to have the best of both worlds ~ the strength of the root stock combined with the attributes of the grafted stock. It's not really propagating (in that you still only have one plant) but you can experiment and have some fun results.
So, there you have it ~ a terrific, easy and FREE way to increase the number of plants you have! Now you can take a portion of your favorite plants and get them started in a new location without losing the ones you already have. In the case of divisions, many of the plants you divide will become healthier and more attractive as a result.