Plectranthus is a large genus of flowering plants belonging to the family Lamiaceae, which includes mint, thyme and most other fragrant herbs. More than 300 species and countless cultivars belong to the genus Plectranthus, including a heavily flowering cultivar called 'Mona Lavender.' The purple flowers and striking bicolored foliage of 'Mona Lavender' charms many gardeners, particularly those looking for a compact perennial shrub to grow in shaded locations. Like most types of hybrid Plectranthus, 'Mona Lavender' grows readily from herbaceous cuttings and will quickly mature, reaching a height of 24 inches within one growing season.
Combine equal measures perlite, sharp sand and coir to create a sterile, nutrient-poor rooting medium. Fill a 4-inch plastic pot with the mixture.
Select a tip or stem cutting from a healthy, vigorous Plectranthus 'Mona Lavender' plant in spring or summer. Choose a 6-inch-long portion of stem with several sets of leaves but no flower buds. Make a straight cut with a pair of floral snips.
Strip off the leaves from the lower half of the cutting. Insert the Plectranthus 'Mona Lavender' cutting into the prepared pot of soil up to the lowest set of leaves.
Set the potted Plectranthus 'Mona Lavender' on a propagation mat set to between 70 and 75 degree Fahrenheit near a source of moderately bright light.
Drizzle 1/4 cup of water into the perlite mixture around the base of the cutting. Water the cutting with 1/4 cup of water whenever the mixture dries out.
Check for roots in six to eight weeks by carefully attempting to lift the Plectranthus 'Mona Lavender' cutting from the rooting medium. Roots will prevent the cutting from moving.
Transplant the Plectranthus 'Mona Lavender' cutting a week after rooting. Move it into a 6- to 8-inch pot filled with potting soil, or directly outdoors into a partially shaded bed.