Origin
Hemizonia increscens (Hall ex Keck) Tanowitz, commonly known as the Rosilla Peak tarplant, is a plant species that is indigenous to California in the United States. It belongs to the family Asteraceae and is a member of the genus Hemizonia.
Common Names
The plant Hemizonia increscens goes by several common names, which include the Rosilla Peak tarplant and the Rosilla tarweed. These names are often used interchangeably to refer to this plant species.
Uses
The Rosilla tarweed was traditionally used by Native American tribes as a medicinal plant for various ailments such as colds, fever, and respiratory issues. Its leaves were also used to make poultices for wounds and cuts. Today, Hemizonia increscens is an important plant species in the ecologically sensitive Southern California area. It serves as a vital habitat and food source for several endangered species of insects, birds, and mammals.
General Appearance
The Rosilla tarweed is a shrubby plant that grows up to 50cm tall and 60cm wide. It has sticky glandular hairs, which produce a resinous substance that gives this plant its common name. The leaves are narrow, lanceolate, and 3-10cm long, and the flowers are yellow and button-like with ray and disk florets. It blooms from July to August and is pollinated by insects such as bees and butterflies.
Growth Conditions for Hemizonia Increscens
Light: Hemizonia increscens requires full sun exposure to thrive. It can tolerate some partial shade, but the plant will not grow as vigorously as it would under full sun conditions. The plant should receive at least six hours of sunlight per day.
Temperature: Hemizonia increscens grows best in warm weather conditions. The optimum temperature range for growth is between 75°F and 85°F (24°C and 29°C). The plant can tolerate cooler temperatures, but it may not grow as quickly or robustly.
Soil: Hemizonia increscens prefers well-draining soils with a pH range of 6.0 to 7.5. The soil should be sandy or loamy and rich in organic matter. The plant has low water requirements and can tolerate drought conditions, but it will benefit from occasional watering during dry periods.
Fertilizer: Hemizonia increscens does not require fertilizer to grow. However, applying a slow-release fertilizer in the spring can help to promote healthy growth and flowering.
Propagation: Hemizonia increscens can be propagated from seed or stem cuttings. Seeds can be sown directly into the soil in the fall or early spring. Stem cuttings can be taken in the summer and rooted in a well-draining soil mix.
Cultivation Methods
Hemizonia increscens is native to California and found in several habitats such as grasslands, chaparral, and oak woodlands. To successfully cultivate this plant, it is important to replicate its original habitat. Therefore, choose a location that has well-drained soil, plenty of sunlight and receives moderate water.
Watering Needs
Hemizonia increscens is drought-tolerant and can survive in arid conditions. However, it still requires moderate watering during the growing season. Water the plant deeply once a week or when the soil feels dry to the touch. In winter, reduce the frequency of watering to once a month to avoid waterlogging.
Fertilization
This plant does not require frequent fertilization. However, an annual compost application during fall or spring can boost soil fertility and enhance growth.
Pruning
Pruning helps to maintain the shape and health of the plant. Hemizonia increscens can grow up to four feet tall and three feet wide. To keep the plant compact and attractive, prune it during late winter or early spring before the new growth emerges. Remove any dead or damaged branches and cut back the old stems to encourage new growth.
Propagation of Hemizonia increscens
Hemizonia increscens, commonly known as the "giant hazing star," is a California native shrub that can grow up to three meters tall. To propagate this plant, there are three main methods: seed propagation, cutting propagation, and layering.
Seed Propagation
Seed propagation is most commonly used for Hemizonia increscens. The plant produces small, black seeds that can be collected from the dried flowers. The best time to collect the seeds is in the late summer or early fall when the flowers have turned brown and dry. The collected seeds should be stored in a cool and dry place.
Before sowing, the seeds should be subjected to stratification, a period of cold treatment to break the seed dormancy. Stratification can be achieved by either storing the seeds in the refrigerator for 30 to 60 days or by sowing the seeds directly in the fall to experience natural winter stratification. Once stratified, the seeds can be planted in a well-draining soil mix in the spring or fall.
Cutting Propagation
Cutting propagation is an alternative method to seed propagation. It involves taking cuttings of the plant and rooting them to create new plants. The best time to take cuttings is in the summer when the plant is actively growing. The cuttings should be taken from healthy stem sections that are not woody, are 4 to 6 inches long, and have several nodes.
After taking the cuttings, remove the lower leaves and dip the cut end in rooting hormone. The cuttings should then be planted in a well-draining soil mix and kept moist. To increase the success rate, the cuttings can be covered with a plastic bag to maintain high humidity. Once the cuttings develop roots, they can be transplanted to individual pots or outdoors to a permanent location.
Layering
Layering is a propagation technique that involves causing a stem to root while it is still attached to the parent plant. This method of propagation is best suited for Hemizonia increscens that have low-hanging branches.
To propagate through layering, select a healthy and flexible stem that is 12 to 18 inches long. Bury part of the stem in the soil, leaving the top part exposed with a few leaves. To promote the formation of roots, choose a spot that is likely to remain moist either through watering or natural rainfall. Once the roots have developed, the propagated plant can be separated from the parent plant and transplanted to a permanent location.
Disease Management
Hemizonia increscens is relatively resistant to diseases, but some problems can still be encountered. Here are some common diseases that might affect the plant:
- Botrytis blight: This fungal disease can affect any part of the plant, causing brown spots and wilting. The best way to manage Botrytis blight is to provide good air circulation, remove any infected plant parts, and avoid overhead watering.
- Root rot: Hemizonia increscens is susceptible to root rot caused by soil-borne fungi, especially in poorly drained soil. To prevent root rot, always use well-draining soil and avoid overwatering.
Pest Management
Hemizonia increscens can be affected by several pests. Here are some common pests that might affect the plant:
- Aphids: These tiny insects can suck the sap from the plant, causing stunted growth and deformities. To control aphids, use insecticidal soap or neem oil and encourage beneficial insects, such as ladybugs and lacewings.
- Spider mites: These tiny pests can cause yellow or brown speckling on the leaves and webbing on the plant. To control spider mites, wash the plant with a strong stream of water, use insecticidal soap or neem oil, and avoid overfertilizing.
- Cutworms: These caterpillars can cut through the stems of young plants, causing them to wilt and die. To control cutworms, handpick them off the plant and use a paper collar around the stem base to prevent them from crawling onto the plant.
Regular monitoring of the plant, promoting healthy growth through proper care, and using organic controls for pests would help to keep Hemizonia increscens free from diseases and pests.
