Origin and Common Names
Thermopsis gracilis T.J. Howell var. argentata (Greene) Jepson is a herbaceous perennial plant that belongs to the Fabaceae family and is native to Western North America. It has several common names, including Mountain Golden Pea, Western Golden Bean, and Argentate Thermopsis.
General Appearance
This plant has a unique appearance and can grow up to 50 centimeters tall in full sun. It has bright green, compound leaves with a bluish tint on top that alternate along the stems. The leaves are lanceolate and grow up to 12 centimeters long. The plant produces showy, yellow flowers that bloom in clusters at the top of the stems from May to August. The flowers are about 1.5 centimeters long and droop down from the stem. The plant's seed pods are linear and up to 5 centimeters long, and the seeds are dark brown and shiny.
Uses
Thermopsis gracilis T.J. Howell var. argentata has several potential uses in landscaping and gardening due to its attractive flowers and foliage. It is also used as an ornamental plant in rock gardens, pollinator gardens, and coastal bluffs. Additionally, some indigenous cultures use this plant to treat ailments such as colds and coughs. However, it is essential to note that the plant contains the alkaloid cytisine, which is toxic when ingested in large quantities and can cause respiratory failure. Therefore, it is crucial to be cautious while using this plant for medicinal purposes.
Light conditions
Thermopsis gracilis T.J. Howell var. argentata requires full sunlight to partial shade for optimal growth. The plant prefers open areas and clearings in forests, meadows, and rocky slopes where it can receive full sunlight for a significant portion of the day.
Temperature tolerance
The preferred temperature range of this plant varies across its range, but it generally prefers cooler temperatures than other members of the genus. In the warmest areas of its range, it tends to grow at higher elevations where temperatures are cooler. In the cooler areas, it can tolerate temperatures down to -40 degrees Fahrenheit (-40 degrees Celsius).
Soil requirements
The plant grows well in well-drained soil that is not too rich in nutrients. It tolerates acidic and alkaline soils, but it prefers a slightly acidic to neutral pH between 6.0 and 7.5. It can grow in soils that are thin and rocky, but it prefers soils that are deeper and more fertile. The plant can tolerate drought, but it will not grow well in excessively wet soils.
Cultivation Method
The Thermopsis gracilis T.J. Howell var. argentata (Greene) Jepson is a hardy plant that can grow either in full sun or partial shade. Before planting, you should prepare the soil by tilling and removing any weeds or rocks. The plant prefers well-drained soil, so you may need to amend it with sand or gravel to improve drainage. You can then plant the plant in the soil at a depth of about two inches. Ensure that you space the plant about 6 - 12 inches apart to provide enough room for growth.
Watering Needs
Thermopsis gracilis T.J. Howell var. argentata (Greene) Jepson needs moderate watering during its growing season. You should water it once a week or check if the soil is dry 2-3 inches deep before you water. Ensure the water doesn't pool around the plant as it can lead to root rot. When watering, you can use a watering can or a hose that has a soft spray nozzle to prevent soil erosion, which can displace the plants.
Fertilization
The plant doesn't require a lot of fertilization, but you can use nitrogen-rich fertilizer once a year during planting or early spring. It can help the plant grow better by providing enough nutrients. Avoid applying too much fertilizer as that can affect the plant's growth. If you are transplanting, you can add a phosphorus-rich fertilizer to help with root development.
Pruning
Cutting back after the growing season is beneficial to its growth so that new growth emerges in the spring. Cut back the plant to about 5 inches above the soil level. Trimming back the bush helps to keep a tidy area and allows for the plant to grow better in the following year. You can also remove the spent flowers during the growing season to provide nutrients to the plant and maintain its appearance.
Propagation of Thermopsis Gracilis T.J. Howell Var. Argentata (Greene) Jepson
Thermopsis gracilis T.J. Howell var. argentata (Greene) Jepson, commonly known as the mountain goldenbanner, is a perennial plant that produces beautiful golden-yellow flowers. If you'd like to propagate this plant, you can do so using various methods such as division, root cuttings, and seedlings.
Division
Division is a technique used to propagate mature plants by separating them into smaller sections. You can use this method to propagate Thermopsis gracilis by digging up the plant and carefully dividing the root system into smaller sections. Be sure to cut cleanly through the roots and replant the divided sections immediately.
Root Cuttings
Root cuttings involve taking a piece of a plant's root system and using it to create a new plant. Cut and remove a section of the root, spray the cut surface with fungicide, and plant the root in damp soil. Place the container in a shaded area and cover it with plastic to trap moisture. Once the roots and new growth have developed, you can transplant the new plant into a permanent pot or in your garden.
Seedling
If you want to grow Thermopsis gracilis from seed, you can collect the ripe pods in late summer or fall when they have turned brown. Soak them in lukewarm water for 24 hours and sow the seeds in well-drained soil. Cover the seeds with sand or soil to keep them moist, and place them in a warm, shady area. Germination usually occurs in 10 to 30 days depending on the moisture and temperature. Once the seedlings have grown several inches tall, you can transplant them into permanent pots or the garden.
Disease Management
Thermopsis gracilis var. argentata is generally known for its resistance to most diseases. However, several diseases may still affect this plant. These include phytophthora root rot, leaf-spots, and powdery mildew.
Phytophthora root rot is caused by the soil-borne fungus Phytophthora. The first symptoms of this disease are the wilting and browning of leaves, followed by the decay of the stem and eventual death of the plant. The best way to manage this disease is by practicing crop rotation, ensuring proper drainage, and avoiding overwatering the plant.
Leaf-spots are caused by different bacteria and fungi that infect the leaves of the plant. This disease is usually distinguished by small, dark spots on the leaves that may enlarge over time. Applying fungicide and removing the infected leaves can help manage this disease most effectively.
Powdery mildew is another common disease that can affect this plant. This disease is a fungal infection characterized by the presence of a white powdery substance on different parts of the plant. The best way to manage this disease is by avoiding over-crowding of the plant, using a fungicide, and promoting good air circulation around the plant.
Pest Management
Thermopsis gracilis var. argentata is also vulnerable to pest attacks. The common pests that may affect this plant include spider mites, aphids, and thrips.
Spider mites are tiny pests that attack the plant's leaves, sucking the sap of the plant and causing yellowing and browning of the leaves. To manage this pest, one can use a miticide or insecticidal soap solution and keep the soil moist enough to discourage the mites from infesting the plant.
Aphids, on the other hand, are tiny insects that appear in clusters on the leaves, flowers, and stems. These pests cause damage on the plant by sucking its sap and leaving it prone to other diseases. To control aphids, one can spray the plant with a blast of water or an insecticide solution and remove any heavily infested leaves.
Finally, thrips are small, slender insects that feed on the leaves and flowers of the plant, leaving behind silvery marks and scars. To manage this pest, one can use insecticidal soap solution or neem oil, remove any heavily infested leaves, and practice high standards of crop hygiene.
