Origin
Corethrogyne filaginifolia var. robusta, commonly known as California aster, is a species of plant that is native to western North America, specifically California and northern Baja California, Mexico.
Common Names
Corethrogyne filaginifolia var. robusta is also commonly known as California aster, robust aster, and Santiago Peak aster.
Uses
California aster has historically been used by indigenous peoples for medicinal purposes. The leaves and flowers were used to make a tea that was believed to help with coughs, fevers, and respiratory ailments. Additionally, California aster is used in modern-day landscaping as a drought-tolerant and attractive ornamental plant.
General Appearance
California aster is a perennial herb that typically grows 1-3 feet tall. It has small, daisy-like flowers that range in color from lavender to pink, and bloom in the late summer to early fall. The leaves are narrow and linear, and are covered in fine hairs that give them a somewhat fuzzy appearance. California aster prefers full sun and well-drained soil, and is typically found in coastal sage scrub and chaparral habitats.
Light Requirements
Corethrogyne filaginifolia var. robusta is adapted to full sun exposure, and it requires direct sunlight for the majority of the day. This plant cannot tolerate shade and may experience stunted growth or die if it does not receive enough sunlight.
Temperature Requirements
This variety of Corethrogyne filaginifolia is native to California and thrives in a Mediterranean climate, with mild and wet winters and hot and dry summers. The ideal temperature range for growth is between 60 °F and 80 °F (15.6°C and 26.7°C), but it can tolerate temperatures below freezing for a short period.
Soil Requirements
Well-drained soil is essential for the growth of Corethrogyne filaginifolia var. robusta. This plant does not tolerate standing water around the roots and is highly susceptible to root rot. The soil pH should be slightly acidic to neutral, between 6.0 and 7.5. It grows well in sandy, loamy, and rocky soils that are low in nutrients because it has a minimal need for fertilizer.
Cultivation Methods
Corethrogyne filaginifolia (Hook. & Arn.) Nutt. var. robusta Greene, commonly known as ‘California aster,’ is a sturdy plant that grows well in sunny and dry locations. The plant has a deep root system and can tolerate drought conditions well. The best time to plant California aster is in the spring or early summer.
The ideal soil type for this plant is sandy or loamy soil that is well-drained and has a neutral to slightly acidic pH. Before planting, loosen the soil and add some compost or well-rotted manure to improve soil quality.
Watering Needs
As mentioned earlier, California aster is drought tolerant, so it can survive on minimal water. However, it is essential to water the plant regularly during the first few weeks after planting until it establishes its roots. After that, water the plant only when the soil becomes dry to the touch.
One thing to keep in mind is that despite its drought tolerance, the plant may need more water during prolonged dry spells. In such situations, deep-watering the soil every two weeks is sufficient to maintain the health of the plant.
Fertilization
Corethrogyne filaginifolia (Hook. & Arn.) Nutt. var. robusta Greene, grows well without added fertilizers. However, if you want to encourage growth and increase the bloom, you can add some balanced fertilizer (10-10-10) once in spring and once in fall.
While adding fertilizer, avoid over-fertilization, as it can lead to the development of weak and leggy plants that may not produce many flowers.
Pruning
Corethrogyne filaginifolia (Hook. & Arn.) Nutt. var. robusta Greene, requires minimal pruning. However, you can pinch the plant back in early summer to promote bushy growth. Deadheading spent blooms will also encourage the development of new flowers.
It is essential to maintain the shape of the plant and prevent it from becoming too leggy by cutting back any wayward branches that stick out. Prune your plants once per year during late winter or early spring.
Propagation of Corethrogyne filaginifolia var. robusta
Corethrogyne filaginifolia var. robusta, also known as the California aster, is a perennial plant that can grow up to 4 feet tall. The plant is native to California and requires a sunny position with well-draining soil.
Propagation by Seed
The easiest and most common propagation method for Corethrogyne filaginifolia var. robusta is by seed. Seeds can be obtained from the plant's flowers, which bloom from June to September. The seeds should be collected just before they begin to fall off the plant.
Once the seeds have been collected, they should be cleaned and stored in a cool, dry place until planting. To promote germination, the seeds should be cold stratified for two to four weeks before planting in the spring.
Seeds can be sown directly in the ground or started indoors and transplanted once they have sprouted. The seeds should be covered with a light layer of soil and watered regularly until they germinate. It can take up to two weeks for the seeds to germinate.
Propagation by Division
Corethrogyne filaginifolia var. robusta can also be propagated by division. This method involves dividing an established plant into smaller sections and replanting them.
Division should be done in the spring when new growth is beginning to emerge. The plant should be dug up, and the root ball should be separated into sections. Each section should have a good portion of roots and healthy foliage.
The sections can be replanted in individual pots or directly in the ground. They should be watered regularly until new growth appears.
Propagation by Cuttings
Corethrogyne filaginifolia var. robusta can also be propagated by cuttings. This method involves taking a small cutting from an established plant and rooting it to form a new plant.
Take cuttings in the spring, when new growth is beginning to emerge. Cut a stem approximately 4 inches long, just below a node. Remove the lower leaves, leaving only a few at the top of the cutting.
The cutting should be placed in a well-draining potting mix and watered regularly. It can take several weeks for the cutting to root and begin to grow.
Propagation by cuttings can be more challenging than propagation by seed or division but can be a useful method for propagating plants that do not produce many seeds.
Disease Management
Corethrogyne filaginifolia var. robusta is generally healthy and has minimal susceptibility to diseases. However, it can still be affected by fungal and bacterial infections.
Fungal Infections:
Fungal infections are common in plants and depend on environmental conditions such as humidity and temperature. The most common fungal infections that affect C. filaginifolia var. robusta include powdery mildew and rust.
To manage powdery mildew, the affected leaves should be removed and destroyed immediately to prevent the spread of the fungus. Spraying with a fungicide can also help to manage the disease. Rust can be controlled by pruning the infected stems and using a fungicide spray.
Bacterial Infections:
Bacterial infections in C. filaginifolia var. robusta can lead to wilting and yellowing of leaves. The most common bacterial infection that affects this plant is bacterial leaf spot.
To manage bacterial infections, it is recommended to remove and destroy the infected plants. The use of a copper-based fungicide can also help manage the spread of the bacteria.
Pest Management
C. filaginifolia var. robusta is generally not heavily affected by pests. However, certain insects can still cause damage to the plant.
Spider Mites:
Spider mites are a common pest that can affect C. filaginifolia var. robusta. These pests can cause yellowing and bronzing of leaves, as well as webbing.
To manage spider mites, it is recommended to increase humidity around the plant by misting it regularly. The use of insecticidal sprays can also help to control the population of spider mites on the plant.
Aphids:
Aphids are another common pest that can affect C. filaginifolia var. robusta. These pests can cause stunted growth and yellowing of leaves.
To manage aphids, it is recommended to use insecticidal soap or neem oil to control the population. Another method is to release natural predators such as ladybugs, lacewings, or parasitic wasps.
