Do you want to increase the number of plants in your garden or home? Is it time to thin herbaceous perennial plants that are crowded or have centers that are dying out? Do you want to share your favorite plants with friends and relatives?
It's called division, and you can do it yourself. You need a few basic supplies for each type of plant, a willingness to experiment, some basic knowledge about each plant's needs, and soon you'll have healthy, vigorous new plants. Here are a few ways to divide perennial plants:
Divisions should be made when the plant is dormant. In most instances, dig up the whole plant. Remove any dead, damaged or diseased portions and cut back any remaining top growth. Gently dunking the roots in water may help wash away excess soil, making it easier to see each rooted crown. Divide portions from the main plant with a sharp shovel or garden knife. Replant selected divisions into a prepared bed or container. Place the plant at the same depth as the parent plant, gently firm the soil around the new plant and water thoroughly.
If the crowns of the plant are not joined (day lilies, Japanese iris, Hosta for example), gently pull, pry or cleanly cut the plants apart. If the crowns are joined by horizontal stems (as the rhizomes found in bearded iris), cut the stems and roots with a sharp knife or blade to minimize injury. If the crown is growing from a tuberous-rooted stem, great care must be taken to ensure the part cut from the parent plant keeps the growing tip (closest to the main plant) upright when replanted. (These plants include Sweet Potato, Dahlia, Bleeding Heart, Anemone, and Tuberous Rooted Begonia.)
When planting new divisions, place in clusters of 3 - 5 crowns. This will create a more substantial and pleasing appearance. Herbaceous perennials commonly need division every three to four years. Plants needing division may be identified by finding large clumps with nearly-dead centers or clumps that are crowding out surrounding plants. Plants with more than one rooted crown (growing tip) may be divided and the rooted crowns planted separately.
Bulbous and corm forming plants can be propagated by division by simply separating newly formed bulblets/cormels from the parent plant. Separate bulb clumps every 3 to 5 years for largest blooms and to increase bulb population. Dig up the clumps after the leaves have withered. Gently pull the bulbs apart and replant them immediately so their roots can begin to develop. Small, new bulbs may not flower for 2 -3 years, but large ones should bloom the first year.
Tiny cormels form around the parent corm. After the leaves mature and wither, dig up the corms and allow them to dry in indirect light for 2 - 3 weeks. Remove the cormels by gently separating the new corm from the old corm. Store in a cool place until planting time. The leaves of bulbs and corms must be allowed to mature and wither to ensure the plant has stored enough energy to produce next year's bloom. Plant spring-bloomers where they are hidden by summer flowers and plants, if desired.
Finally, some plants help us by layering with stolons or runners (well known examples are strawberries, hens-and-chicks, and spider plants.) A stolon is a horizontal, often fleshy stem that can root, then produce new shoots where it touches soil or a growing medium. A runner is a slender stem that originates in a leaf axil and grows along the ground, producing a new plant at its tip. Propagate plants with stolons or runners by severing the new plant from their parent stems. Plantlets at the tips of runners may be rooted while still attached to the parent or they can be detached and placed in a rooting medium.