Plants can be propagated from leaf or stem cuttings, seeds or root cuttings. When propagated by root cuttings, a section of the plant's root is used to produce a new plant. Some root cuttings produce green shoots that form roots of their own, while others produce roots first and send up shoots of a new plant. The process of growing the root cutting is basically the same regardless of how the new plant forms.
Collect root cuttings in late fall or winter when the plant is dormant by gently digging under the desired plant to expose the roots. Use caution not to disrupt the entire root system. Look for healthy firm roots that are between 1/4 and 1/2 inch in diameter.
Cut the root into 1- to 2-inch lengths with a sharp knife. Look for small buds or rootlets emerging from the main root. Cut root sections with at least four buds.
Place the root cuttings on moist rooting medium. Root cuttings can be started in moist vermiculite, peat moss or perlite. Avoid commercial potting soil, as it is too heavy for rooting cuttings and may promote rotting.
Cover with 1/2 inch of rooting medium. Cover with clear plastic to maintain humidity and moisture levels. Place the cuttings in a warm area that receives indirect light. Cuttings overheat quickly when exposed to direct sunlight.
Keep the rooting medium moist until new shoots appear and adequate roots have formed. Check by tugging the new shoots gently. If they resist, roots have formed.
Transplant new plants to individual 4-inch pots when roots are established. Place in the appropriate lighting for the specific plant.
Start root cuttings in the soil in the garden, if preferred. Lay the sections in the soil and cover them with 1/2- to 1-inch of soil. Keep the soil moist and observe for the emergence of new shoots.