The ‘blue lips plant’ (Plectranthus ernstii) is a captivating succulent known for its distinctive flower structure. This fascinating perennial has become a favorite among plant enthusiasts due to its unique appearance and relatively straightforward care requirements. Its compact growth habit and intriguing blooms make it a desirable addition to various plant collections.
Understanding the Blue Lips Plant
Plectranthus ernstii is a semi-succulent subshrub belonging to the Lamiaceae family, which also includes mints. It originates from subtropical South Africa, growing in humus-rich pockets within rock crevices. The plant typically reaches a height of up to 25 cm (10 inches) and develops greyish, jointed stems that can swell at the base, sometimes resembling a potato-like caudex as it ages.
The plant earns its common name, ‘blue lips,’ from its unique inflorescence. Its small, two-lipped flowers are pale bluish-mauve to whitish with darker markings, arranged in whorls along a short flowering stem. These flowers appear primarily in autumn in their natural habitat. The aromatic leaves also give off a pleasant scent when touched.
Caring for Your Blue Lips Plant
Light Needs
Plectranthus ernstii thrives in bright, indirect light. While it can tolerate some morning sun, shield it from harsh afternoon direct sunlight, which can scorch its leaves. Adequate light promotes compact growth and vibrant foliage, preventing leggy stems.
Watering Practices
As a semi-succulent, Plectranthus ernstii stores water in its swollen stems and leaves, making it drought-tolerant. Water thoroughly when the soil has almost completely dried out between waterings. Ensure excess water drains away freely. During cooler winter months, reduce watering significantly as the plant’s growth slows.
Soil Requirements
Well-draining soil is crucial for the health of Plectranthus ernstii to prevent waterlogging and root issues. A succulent or cactus potting mix is suitable, or amend a regular potting mix with materials like perlite, pumice, or coarse sand to enhance drainage.
Temperature and Humidity
This plant prefers moderate to warm temperatures, ideally between 15°C and 25°C (59°F to 77°F). It is sensitive to frost and should be protected from temperatures dropping below 10°C (50°F). Plectranthus ernstii tolerates average household humidity levels and does not require high humidity.
Fertilizing
During the active growing season in spring and summer, feed your Plectranthus ernstii lightly. Use a balanced liquid fertilizer, diluted to half or quarter strength, approximately every four to six weeks. Avoid over-fertilizing. In autumn and winter, stop fertilizing when the plant’s growth naturally slows.
Propagating Blue Lips Plant
Propagating Plectranthus ernstii is primarily achieved through stem cuttings. The best time to take cuttings is during spring or early summer when the plant is actively growing. Select a healthy stem section about 4-6 inches long with at least 2-4 nodes. Remove leaves from the lower portion, leaving a few at the top.
Allow the cut end to “callus” or dry for a day or two; this helps prevent rot. Once callused, place the cutting directly into a well-draining potting mix, such as perlite and vermiculite, or root in water. Keep the soil slightly moist until roots develop, which typically occurs within a few weeks.
Common Challenges and Solutions
One of the most frequent problems encountered with Plectranthus ernstii is root rot, which typically results from overwatering or poorly draining soil. If leaves begin to yellow or the plant appears wilted despite moist soil, it may indicate root rot. To address this, allow the soil to dry out completely between waterings and ensure your pot has adequate drainage holes.
Insufficient light can cause the plant to become leggy, with elongated stems and sparse foliage, as it stretches in search of light. Moving the plant to a brighter location with more indirect light will encourage bushier, more compact growth. Conversely, intense direct sunlight can lead to leaf scorch, appearing as brown or bleached spots.
While Plectranthus ernstii is generally robust, it can occasionally encounter common houseplant pests such as mealybugs or spider mites, particularly if stressed. Inspect your plant regularly for any signs of pests, such as sticky residue or tiny webs. A gentle spray with insecticidal soap or neem oil can help manage these infestations.