Ask Mr. Smarty Plants

At the Lady Bird Johnson Wildflower Center, we concentrate on the protection and propagation of plants native to North America. While the Plectranthus is a native of South Africa, we are happy to pass along the information we found on it.

The Plectranthus "Mona Lavender" is the result of very intensive hybridizing in its native South Africa. It is a quick-growing perennial shrub, reaching 24 to 30 inches in height. When it receives sun, it tends to stay smaller and more compact, and does very well in either shaded or partly sunny positions. In your location in New York, you will certainly need to bring the plant in before the first frost. It needs a rich soil, and watering every few days, as well as fertilizing every 6 to 10 weeks. We really can't help you much with whether infestations on the leaves or the soil will damage your house plants. The best practice is to examine it very closely before you bring it in, perhaps using a strong spray of water on the leaves to dislodge any very small pests. If the soil began as a sterilized potting soil, there shouldn't be much danger of pests in that. If you are still concerned, you might "quarantine" it for a while, away from the other house plants, perhaps in a garage, and see if the warmer interior air brings out any bugs.

Since this plant is a native of a much-warmer climate, we don't feel it's necesssary to warn you about allowing the plant to grow in the soil outside. If it can't survive your winters, it's unlikely to escape from cultivation and become an invasive.