Overview
Sonchus asper (L.) Hill subsp. glaucescens (Jord.) Ball, also known as Prickly Sow-thistle, is a flowering plant that belongs to the Asteraceae family. This plant is widely distributed across Europe, western Asia, and North Africa. It is considered an invasive species in some regions.
Common Names
The plant Sonchus asper (L.) Hill subsp. glaucescens (Jord.) Ball has several common names, including Prickly Sow-thistle, Spiny Sow-thistle, Prickly Milk Thistle, and Spiny-leaved Sow-thistle.
Appearance
The plant can grow up to 3 feet tall. The leaves are pale green and have a spiny texture, measuring about 10 to 30 cm long and 5 to 20 cm wide. The leaves are arranged alternately on the main stem. The stem is used as a way to differentiate subspecies, as S. asper subsp. asper stems have rough hairs while S. asper subsp. glaucescens stems have smooth hairless skin.
The Prickly Sow-thistle blooms from May to October, producing vibrant yellow flowers that are about 2 cm in diameter. The flowers are located at the tips of the plant's branches and have multiple florets. After flowering, the plant produces achenes, which are small, dry, and spiny fruits that measure about 3 to 4 mm in length.
Uses
Sonchus asper (L.) Hill subsp. glaucescens (Jord.) Ball has been used in traditional medicine to treat several ailments, including liver disorders, skin diseases, and digestive issues. The leaves are believed to have anti-inflammatory and diuretic properties.
The plant is also used as a food source in some cultures. The leaves of the plant are often consumed raw or cooked and can be prepared like spinach. The young shoots and flower stalks are also edible raw or cooked.
However, despite its medicinal and food applications, the plant is considered a weed and can be harmful to native wildlife, as it competes with the growth of other plants and can create a monoculture if left unchecked.
Light Requirements
The plant Sonchus asper subsp. glaucescens thrives in full sun exposure. It requires at least 6 hours of direct sunlight per day.
Temperature Requirements
This plant sub-species is adaptable to different temperature ranges. It can grow well in temperatures ranging from 18°C to 30°C. However, it is worth noting that this plant sub-species can withstand a minor frost event.
Soil Requirements
The plant Sonchus asper subsp. glaucescens grows best in well-draining soils that are moderately fertile. It prefers slightly acidic to neutral (pH 6.0 to 7.0) soils. This plant can tolerate mildly saline soils and is commonly found growing near the sea coast.
Cultivation Methods
The Sonchus asper (L.) Hill subsp. glaucescens (Jord.) Ball, also known as the prickly sowthistle, tolerates extreme climates and can grow in various soil types. However, it prefers well-draining soil with a pH between 6.1 to 7.8. You can cultivate it from seeds or cuttings in the spring or fall. Seeds should be sown directly in the garden bed, 1/8 inch deep, and around 6 inches apart. Once the seedlings reach 2 to 3 inches tall, thin them to at least 12 inches apart. Cuttings should be planted in well-draining potting soil, and you should keep them moist until new growth appears.
Watering Needs
The prickly sowthistle prefers evenly moist soil, but excessive watering can lead to root rot. During the growing season, water the plant regularly to keep the soil slightly moist. You can check the soil by penetrating a finger two inches deep into the soil. If it feels dry, it's time to water. In the dormant season, reduce watering frequency significantly, but do not let the soil dry out completely.
Fertilization
Prickly sowthistle plants are not heavy feeders and do not require regular fertilization. However, if the soil is poor, you may fertilize in the early spring with a balanced and slow-release fertilizer. Apply the fertilizer according to the package instructions and water the plant afterward.
Pruning
Prickly sowthistle will self-seed and spread vigorously if not pruned regularly. Therefore, it's important to remove the flowers before they go to seed. Alternatively, you may deadhead by cutting off the spent blooms before seeds develop. Additionally, you can prune the plant to maintain its shape and promote bushier growth. The best time to prune is in the early spring before new growth appears.
Propagation of Sonchus asper subsp. glaucescens
Sonchus asper subsp. glaucescens, commonly known as Spiny Sowthistle, can be propagated through several methods.
Seed Propagation
The most common method of propagating Spiny Sowthistle is through seeds. The plant produces a large number of seeds, which are easily collected and stored. Seeds should be sown in the spring or autumn, in a well-drained soil mix. It is important to keep the seeds moist until germination, which usually takes 7-14 days. Once the seedlings have developed a set of true leaves, they can be potted up individually and grown on until they are large enough to be planted in their final positions.
Division
Spiny Sowthistle can also be propagated through division. This method is most suitable for plants that are several years old and have developed larger clumps. The best time to divide the plants is in autumn or early spring, when they are beginning to grow actively. The plant should be lifted carefully, and the clumps should be separated into smaller sections that each contain a portion of the root and some shoots. These smaller sections can then be replanted into prepared soil. It is important to keep the plants well-watered until they have established new roots.
Cuttings
Although Spiny Sowthistle does not root easily from cuttings, it is possible to propagate the plant using this method. Take a stem cutting from a young, healthy plant, approximately 10cm in length, and remove all the leaves except for the top few. Dip the cutting into rooting hormone powder and insert into a free-draining soil mix. Cover the pot with a clear plastic bag to prevent moisture loss, and keep the soil moist. It may take several weeks for the cutting to develop roots, and it should only be potted up individually once it has several roots and a healthy stem.
Disease Management
Sonchus asper subsp. glaucescens is generally a hardy plant, but it is still prone to diseases that can affect its overall health and productivity. Some of the common diseases that might affect this plant are:
- Rust: This disease is highly contagious and can spread quickly from one plant to another. It can be identified by yellow or orange spots on the leaves or stems. To manage rust, it is recommended to prune all the infected parts of the plant and apply a suitable copper-based fungicide.
- Powdery mildew: It is identified by white powdery substance on the leaves and stems. This disease can stunt growth and cause leaves to curl or wilt. To manage powdery mildew, it is recommended to spray the infected plant parts with a mixture of baking soda and water or a fungicide containing potassium bicarbonate.
- Phoma: This disease causes stem rot, which can eventually lead to the collapse of the plant. It is identified by dark brown lesions on the stems or leaves. To manage Phoma, it is recommended to remove all the infected plant parts and avoid overwatering the plant.
Pest Management
Sonchus asper subsp. glaucescens can also be affected by pests that can cause significant damage to the plant. Some of the common pests that might affect this plant are:
- Aphids: These tiny insects can cause curling and distortion of leaves, and also attract other pests. To manage aphids, it is recommended to spray the plant with insecticidal soap or neem oil.
- Spider Mites: Common in hot and dry conditions, these pests can cause discoloration and webbing on the leaves. To manage spider mites, it is recommended to spray the plant with water to increase humidity levels or use a suitable miticide.
- Caterpillars: These pests can cause severe damage to the plant by eating large sections of leaves. To manage caterpillars, it is recommended to remove them manually and use a suitable insecticide if needed.
