Origin
Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson, commonly known as Large-leaved Thermopsis, is a species of flowering plant in the pea family Fabaceae. It is native to the western United States, including California, Oregon, Idaho, and Montana.
Common Names
Aside from Large-leaved Thermopsis, this plant is also commonly referred to as Bigleaf Thermopsis or Silverleaf Thermopsis.
Uses
Thermopsis macrophylla Hook. & Arn. var. argentata has a number of uses. Historically, Native American tribes have used this plant for medicinal purposes, such as to treat wounds and respiratory problems. This species is also a popular ornamental plant, commonly grown in gardens and wildflower meadows for its beautiful yellow flowers that bloom in the early summer. Moreover, this plant is considered useful for erosion control and land restoration projects, due to its ability to thrive in disturbed areas.
General Appearance
Thermopsis macrophylla Hook. & Arn. var. argentata is a perennial herb with a tall, upright growth habit, reaching up to 3 feet in height. Its leaves are large and pinnately divided, with silvery green leaflets that are soft to the touch. The flowers are bright yellow and pea-like, arranged in loose clusters at the top of the plant. Flowering typically occurs from late May through early July. After the flowering period, Thermopsis macrophylla Hook. & Arn. var. argentata forms a seed pod that contains up to ten seeds.
Growth Conditions for Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson
Light: This plant species thrives in full sunlight and requires at least 6 hours of direct sunlight to grow properly. If grown in the shade, the plant tends to become straggly and weak.
Temperature: This plant species prefers cooler temperatures and does well in USDA hardiness zones 3 to 7. The ideal temperature for this plant is between 60°F to 70°F. When grown in higher temperatures, the plant tends to wilt and become stressed which can affect its growth and survival.
Soil Requirements: Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson grows well in loamy, well-drained soils. The soil pH should be slightly acidic to neutral, with a range of 6.0-7.5. This plant species requires adequate moisture but with good drainage. The soil should not be waterlogged, as this can lead to root rot.
Fertilizer: Fertilizer is not generally required for this plant. However, if the soil is poor, a light application of compost or well-rotted manure can be beneficial in early spring before new growth starts.
Water: This plant species requires moderate watering. Overwatering can cause root rot, while under-watering can make the plant susceptible to wilting. Ensure that the soil is moist but not saturated. During periods of drought, the plant should be watered more frequently.
Cultivation methods
Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson thrives best in well-drained soils and prefers full sun to partial shade. It is a hardy plant and can do well in various types of soil, including sandy, loamy, and rocky soils.
The plant propagation can be done by seeds or division. You can sow the seeds in the fall, or if you prefer division, do it in spring.
Watering needs
Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson is relatively drought tolerant, and overwatering can lead to root rot. Therefore, it is advisable to water only when necessary, preferably when the soil is dry to touch. Monitor the soil moisture level during the growing season, and adjust the watering accordingly.
Fertilization
The plant does not require much fertilizer, and overdoing it can lead to poor flowering. Therefore, it is advisable to use a balanced fertilizer in the early spring, before the growing season begins. Alternatively, the use of an organic mulch can supply the necessary nutrients to the plant.
Pruning
Pruning is not necessary for Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson but removing the spent flower spikes can encourage more blooms. Also, in the fall, after the foliage has died back, you can cut back all the stems to the ground level, a process that helps to control the plant's size and shape.
Propagation of Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson
Propagation of Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson can be done through seeds or vegetative means.
Propagation through Seeds
The most common and successful method of propagating Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson is through seeds. The seeds should be collected in the fall after the pods have dried and turned brown. To increase the chances of germination, the seeds can be soaked in warm water for 24 hours. After soaking, the seeds can be planted in a well-draining soil mix with a pH range of 6.0 to 8.0. The soil should be kept moist, but not overly wet. Germination normally takes place within 2 to 4 weeks.
Propagation through Vegetative Means
Propagation through vegetative means, such as cuttings or division, can also be done, but is less successful. Cuttings should be taken from the current year's growth in the summer, and should be approximately 4 to 6 inches long. The cuttings can be treated with a rooting hormone and planted in a well-draining soil mix. Division can be done in the spring or fall, with the root ball being carefully separated into smaller sections with a sterile cutting tool, and replanted in a suitable location.
Disease and Pest Management of Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson
Thermopsis macrophylla Hook. & Arn. var. argentata (Greene) Jepson, commonly known as bigleaf thermopsis, is susceptible to certain diseases and pests like any other plant species. Early detection and management of these issues are crucial to preventing severe damage to the plant. Here's a brief overview of the common diseases and pests that may affect the plant and ways to manage them.
Diseases
Fungal diseases: Fungal diseases are one of the most common issues faced by T. macrophylla plants. Powdery mildew, rust, and leaf spot are some of the fungal diseases that may attack the plant. These diseases can be prevented and managed by ensuring proper air circulation, avoiding overhead watering, and removing infected plant parts. Fungicides like copper sprays and neem oil can also help control fungal diseases.
Bacterial diseases: Bacterial wilt and crown rot are two bacterial diseases that may affect T. macrophylla plants. These diseases can spread rapidly and cause severe damage to the plant. Infected plants should be removed immediately to prevent the spread of the disease. Preventive measures like improving soil drainage and avoiding overwatering can help control these bacterial diseases.
Pests
Aphids: Aphids are tiny, sap-sucking insects that may attack T. macrophylla plants. They can be controlled by spraying the plant with insecticidal soap or neem oil. Encouraging natural predators like ladybugs can also help keep aphid populations in check.
Spider mites: Spider mites are common pests that thrive in hot and dry conditions. They may cause yellow or brown spots to form on the leaves of T. macrophylla plants. Spraying the plant with water regularly and keeping the humidity high can help prevent spider mite infestations. Insecticidal soap or neem oil can also be used to control spider mites.
Cutworms: Cutworms are the larvae of certain moth species and may attack T. macrophylla plants. They can be controlled by placing collars around the plant stems or by using bacillus thuringiensis (Bt) insecticide.
Regular monitoring and timely management of these diseases and pests can help ensure a healthy and thriving T. macrophylla plant.
