Plectranthus is a plant genus that is part of the Lamiaceae family. It contains about 350 species of annual and perennial shrubs that are native to Africa, Australia, and the Pacific Islands. The plants feature hairy leaves with white margins and small flowers. These plants are ideal for borders, hanging baskets, or containers. Some problems with growing plants in the Plectranthus genus include pest infestation, especially from mealybugs, and fungal disease, such as leaf spot.
The genus name is derived from the Greek words plectron and anthos, which mean "spur" and "flower," respectively. The common name for these plants is spurflower. Several species have variations on the common name. For example, Plectranthus argentatus is known as the silver spurflower, while Plectranthus madagascariensis is called variegated mint leaf.
Most of the plants in this group are located in the southern hemisphere, from Africa to the Pacific Ocean. P. amboinicus grows in the southern and eastern parts of Africa, while P. australis is native to Australia. P. madagascariensis is distributed across South Africa and Madagascar.
Variegated mint leaf typically grows 3 feet (1 m) tall and spreads a similar length. It is an evergreen shrub that has a spreading or trailing form. The foliage consists of gray-green leaves that are variegated. Variegated leaves have streaks or blotches over the green color. Usually, the gray-white blotches on mint leaf are on the edges, but some leaves have streaks through the center.
This plant grows best in well-draining soil that is fertile and either loamy or sandy. The soil can be either acidic or alkaline, since the variegated mint leaf can thrive in both. Additionally, the area in which it is planted should be sheltered from the wind and partially shaded from the sun.
Most species within the Plectranthus genus are susceptible to damage from mealybugs, which are segmented, oval-shaped insects that are covered in a white wax. They infect every part of the plant, from the roots to the leaves. Mealybugs leave a residue that resembles candle wax on the branches. Mold spores are attracted to the residue and generally cover entire branches.
Another problem which may affect these plants is leaf spot, which is a fungal disease that produces brown or black spots on the leaves. It causes the leaves to curl and eventually drop. Applying a fungicide to the plant may prevent the fungus from spreading.