Origin and Common Names:
Dubautia plantaginea Gaud. var. glandulosa St. John, commonly known as "Kohol? Mountain daisy" or "Kohol? Dubautia", is a flowering plant species endemic to Hawaii. It can be found on the island of Maui, specifically on the slopes of Haleakal? Volcano, in dry shrublands and montane forests at elevations of 2,000 to 7,000 feet.
Appearance:
The Kohol? Mountain daisy is a small perennial shrub, usually growing up to 3 feet tall. Its leaves are thick and leathery, with a lanceolate shape, and grow up to 6 inches long. The plant's inflorescences are composed of clusters of small, white, and yellow flowers which bloom between July and September, attracting a variety of insects and birds.
Uses:
The Kohol? Mountain daisy is not widely used for medicinal, culinary, or industrial purposes, but it holds great ecological significance. The plant is an important part of the unique Hawaiian montane ecosystems, providing habitat and food for a wide range of endemic species such as birds, moths, and butterflies. Additionally, the Kohol? Mountain daisy and other Dubautia plant species are being studied for their potential to store carbon and mitigate climate change.
Light Requirements
Dubautia plantaginea Gaud. var. glandulosa St. John grows best in full sun or partial shade. It can tolerate shade, but it tends to become leggy and produce fewer flowers in shady areas. Therefore, it is recommended to grow the plant where it can receive 6-8 hours of direct sunlight per day.
Temperature Requirements
The plant prefers a moderate climate, with average temperatures around 15 to 21°C (59 to 70°F). It can tolerate some heat and drought, but extreme conditions may cause it to suffer. Dubautia plantaginea Gaud. var. glandulosa St. John grows well in USDA hardiness zones 10 to 11, where the temperature range is about 30°F to 100°F (-1°C to 38°C).
Soil Requirements
Dubautia plantaginea Gaud. var. glandulosa St. John thrives in well-drained soils. It prefers soils that are neutral to slightly acidic with a pH range of 5.5 to 7.0. The soil should be rich in organic matter, and it must be able to hold moisture without becoming waterlogged. Adding compost to the soil can improve its structure and fertility. The plant can tolerate sandy or clay soils, but it requires adequate drainage to prevent root rot.
Cultivation Methods
Dubautia plantaginea Gaud. var. glandulosa St. John thrives well in USDA zones 10 and 11, where temperatures are consistently warm throughout the year. The plant requires well-draining soils that are rich in organic matter. Besides, it prefers partial shade to full sunlight conditions, making it an ideal option for gardens with moderate shade.
Watering Needs
The plant requires regular watering, especially during the hot and dry season to prevent desiccation. However, it is essential to avoid waterlogging the soil as this can cause root rot. Instead, water the plant when the topsoil appears dry to the touch. Consider using a moisture meter to ensure that the soil is moist but not saturated.
Fertilization
It is essential to fertilize Dubautia plantaginea Gaud. var. glandulosa St. John with a balanced fertilizer during the growing season to provide the required nutrients. Consider using a 20-20-20 fertilizer at half the recommended dosage once a month to promote healthy growth. Alternatively, you can use a slow-release fertilizer applied once per season.
Pruning
The plant requires regular pruning to maintain an attractive shape and size. Prune the plant immediately after flowering, usually in late winter or early spring. Consider removing the dead and diseased wood, weak branches, and crossing stems to enhance air circulation and prevent pest and disease infestations. Additionally, removing the spent flowers can stimulate more blossoms, leading to a longer blooming period.
Propagation of Dubautia plantaginea Gaud. var. glandulosa St. John
Dubautia plantaginea Gaud. var. glandulosa St. John, commonly known as ‘Na’ina’i kea or White Tanglehead, is a rare and endemic shrub that grows in dry, rocky areas of Hawaii. Propagation of this plant is necessary to conserve its species and increase its population.
Propagation via Seeds
Propagation via seeds is one of the most feasible methods for Dubautia plantaginea Gaud. var. glandulosa St. John. The seeds need to be collected from mature specimens, and they will require stratification before sowing. Stratification involves storing the seeds in a cool and dry place to break their dormancy. After stratification, the seeds can be sown in well-drained, fertile soil. Germination may begin after several weeks, and the seedlings will require appropriate care, including watering and providing adequate light.
Propagation via Stem Cuttings
Propagation via stem cuttings is another method that can be used to propagate Dubautia plantaginea Gaud. var. glandulosa St. John. It involves taking semi-hardwood cuttings from mature plants during the growing season and treating them with rooting hormone. The cuttings are then planted in well-drained soil and placed in a mist bed or covered with a plastic bag to maintain high humidity. Rooting should occur after several weeks, and the new plants will require adequate light and humidity to establish themselves.
Propagation via Air Layering
Air layering is a propagation method suitable for Dubautia plantaginea Gaud. var. glandulosa St. John, given its thick and woody branches. It involves taking a small branch from a mature plant and scraping off a small portion of its bark. The scraped area is then wrapped with moist sphagnum moss and covered with plastic wrap, which helps to maintain humidity levels. After several weeks, roots should develop, and the branch can be cut off and transplanted into a new pot or in open soil. Air layering allows for the propagation of the plant without damaging the parent plant.
Disease Management for Dubautia plantaginea Gaud. var. glandulosa St. John
Dubautia plantaginea Gaud. var. glandulosa St. John is relatively disease-resistant, but some fungal and bacterial diseases can still affect the plant.
One common fungal disease is powdery mildew, which appears as a white, powdery film on leaves and stems. To manage powdery mildew, avoid overhead watering and maintain good air circulation around the plant. Fungicidal sprays can also be applied.
Bacterial leaf spot is another disease that affects Dubautia plantaginea Gaud. var. glandulosa St. John. It appears as small, water-soaked spots on leaves that eventually turn into brown lesions. To manage bacterial leaf spot, remove infected leaves and avoid overhead watering. Copper-based sprays can also be used.
Pest Management for Dubautia plantaginea Gaud. var. glandulosa St. John
Some pests can also affect Dubautia plantaginea Gaud. var. glandulosa St. John, including spider mites and thrips.
Spider mites are tiny pests that suck the plant's sap, causing yellowing and browning of leaves. To manage spider mites, spray the plant with a strong jet of water to dislodge the pests. In severe cases, insecticidal soap or oil can also be used.
Thrips are small, slender insects that feed on flowers and leaves, causing damage and discoloration. To manage thrips, prune damaged leaves and flowers and remove weeds and debris around the plant to reduce hiding places. Insecticidal sprays may also be used.
