Origin and Common Names
Thermopsis macrophylla Hook. & Arn. ssp. semota (Jepson) Beauchamp is a herbaceous perennial plant native to western North America. It is commonly known as Scarlet Thermopsis or Sierra Lupine.
Uses
The plant has a variety of uses. Indigenous communities have used the plant for medicinal purposes to treat stomach ailments, inflammation, and respiratory issues. Scarlet Thermopsis is also used as an ornamental plant in gardens for its beautiful and bright flowers. Additionally, the plant plays an important role in ecological restoration as it is often used to prevent soil erosion and to restore disturbed habitats.
General Appearance
The plant can grow up to 70 cm in height and has large compound leaves with 9-15 leaflets that are blue-green in color. The stems of the plant are erect and covered in fine hairs. The showy flowers are bright scarlet in color and bloom in the spring and summer. The flowers grow in dense terminal spikes that can reach up to 30 cm long. The plant produces small seed pods that contain several seeds and are slightly curved. Scarlet Thermopsis is easy to cultivate and requires moist, well-drained soil and full sun to partial shade.
Light Requirements
Thermopsis macrophylla Hook. & Arn. ssp. semota (Jepson) Beauchamp requires full sun to grow well. It is adapted to the bright and sunny conditions of open grasslands, meadows, and forest clearings. The plant is also tolerant of partial shade but may produce fewer flowers and have reduced growth rates.
Temperature Range
The plant grows well in temperate regions with cool summers and cold winters. It is hardy to USDA zones 5 to 8, which means it can tolerate temperatures as low as -20°F (-29°C). However, it grows best in areas with temperatures ranging from 65°F to 75°F (18°C to 24°C) during the day and 45°F to 55°F (7°C to 13°C) at night.
Soil Preferences
Thermopsis macrophylla Hook. & Arn. ssp. semota (Jepson) Beauchamp thrives in well-draining soils that are slightly acidic to neutral (pH 5.5 to 7.0). The plant prefers soils that are rich in organic matter and nutrients as it needs sufficient nourishment to produce lush foliage and abundant flowers. It does not grow well in heavy, compacted soils or those that are consistently waterlogged.
Cultivation Methods
Thermopsis macrophylla Hook. & Arn. ssp. semota (Jepson) Beauchamp is a hardy plant that grows well in USDA zones 7 to 9. It prefers to grow in a sunny location but can grow in partial shade. The plant grows in well-drained soils and prefers slightly acidic to neutral soil pH.
You can propagate T. macrophylla through seeds or by dividing the root ball in the fall. Seeds require stratification for successful germination. Sow the seeds in the fall, and they will germinate in the spring. The plant requires minimal care once established.
Watering Needs
T. macrophylla requires regular watering to establish itself and thrive. Water newly planted specimens often and deeply to help the root system grow. The plant prefers evenly moist soil but can tolerate short periods of drought once established. Be careful not to overwater the plant, as this can lead to root rot.
Fertilization
Fertilizing T. macrophylla is not necessary, but it can help the plant grow faster and have more flowers. Apply a balanced fertilizer in the spring when new growth appears. Follow the manufacturer's instructions and be careful not to apply too much fertilizer, as this can damage the plant.
Pruning
T. macrophylla requires minimal pruning. You may remove any damaged or diseased branches as needed. Pruning after the blooming period can help maintain the plant's shape and encourage new growth for the following season. Use clean, sharp pruning shears and cut just above a node or bud. Avoid pruning the plant too much, as it can impact the plant's overall health and flowering ability.
Propagation of Thermopsis macrophylla Hook. & Arn. ssp. semota (Jepson) Beauchamp
There are several ways to propagate Thermopsis macrophylla Hook. & Arn. ssp. semota (Jepson) Beauchamp, including through seeds, division, and cuttings.
Propagation by Seeds
The easiest way to propagate this plant is through seeds. Collect the seeds in fall, sow them immediately, or store them in a cool, dry place for later use. If planting immediately, soak the seeds in warm water for 24 hours to soften the hard outer shell. Plant the seeds in a well-draining potting mix. Cover the pot with plastic wrap or a dome to create a humid environment that can help with germination. Place the pot in a bright, warm spot, but out of direct sunlight. Keep the soil moist but not waterlogged, and within a few weeks, the seeds should germinate.
Propagation by Division
You can propagate this plant through division in early spring when new shoots appear. Carefully remove the entire plant from the ground, gently tease apart the roots, and separate them into smaller sections. Replant each section in a new hole that is twice as wide as the root ball. Water the new plants well and mulch around the base to conserve moisture and suppress weeds.
Propagation by Cuttings
Propagation by cuttings is another option. Take new shoots in spring or early summer and make a cutting that has at least two nodes and several leaves. Remove the lower leaves, dust the cutting with rooting hormone, and then plant it in a well-draining rooting medium. Cover the pot with a plastic wrap or a dome. Keep the soil moist but not waterlogged and make sure the cutting is not drying out. Within a few weeks, the cutting should root, and new growth will appear. Once rooted, plant the new plant in its permanent location.
Disease Management
Thermopsis macrophylla Hook. & Arn. ssp. semota (Jepson) Beauchamp is relatively resistant to most diseases. However, it may become susceptible to fungal infections such as leaf spots, root rot, and powdery mildew.
To prevent leaf spot and powdery mildew, avoid overhead watering and keep the foliage as dry as possible. If required, treat the plant with fungicides as per the manufacturer's instructions. In case of root rot, remove the infected plant, and improve the drainage of the soil to prevent future occurrences.
Pest Management
Thermopsis macrophylla Hook. & Arn. ssp. semota (Jepson) Beauchamp is not generally affected by pests. However, it may get infested by aphids, spider mites, and caterpillars.
To control aphids and spider mites, spray the plant with a strong jet of water to remove them. You can also use insecticidal soap or neem oil as a treatment. For caterpillars, remove them by hand and use Bacillus thuringiensis (Bt) if necessary.
Regularly inspecting the plant for signs of pests and diseases can help in early detection and quick control. It is always advisable to follow the recommended guidelines and instructions while using any pest or disease control measures.
