Origin
Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus, also known as bush lupine, is a species of flowering plant in the family Fabaceae. It is native to western North America, particularly California, Oregon, and British Columbia.
Common Names
The bush lupine has a variety of common names depending on the region. These may include bush lupine, coastal lupine, and dwarf lupine.
Uses
Bush lupine has various uses in both ornamental and ecological settings. As a plant used for landscaping, it can be used as a groundcover or as part of a wildflower garden. In ecology, it is often used in restoration efforts as it is a nitrogen-fixing plant, meaning it converts atmospheric nitrogen into a form that other plants can use. This helps improve soil fertility and health.
General Appearance
Bush lupine is a small, shrubby plant that typically grows between 1 and 4 feet tall. It has leaves that are palmately compound, with 5 to 8 leaflets each. The leaves themselves are generally green, but may be tinged with blue or gray and covered in fine hairs. The plant produces spikes of blue-purple or blue-violet flowers that bloom in the late spring or early summer. These flowers are attractive to bees and butterflies, making it a great addition to a pollinator garden.
Light Requirements
Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus thrives in full sun conditions. In fact, it requires a minimum of six hours of direct sunlight a day. The plant grows well in open fields, meadows, and other locations that provide ample light exposure. Insufficient light exposure may lead to stunted growth and reduced flowering.
Temperature Requirements
This plant species prefers mild temperatures with average to cool summers and mild winters. It is well-suited for the USDA plant hardiness zones 7-9, where the average temperatures range from 10 to 30°C. Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus is hardy to frost and can tolerate occasional temperature drops to -12°C.
Soil Requirements
The plant requires well-draining soils that are rich in organic matter and have a pH range of 5.5 to 7.5. Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus can tolerate slightly acidic soils; however, higher pH levels may hinder its growth. Additionally, the plant requires soils that are moist but not waterlogged. Sandy loam and loam soils are ideal for the growth of this plant species.
Cultivation methods
Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus is a popular ornamental plant that requires well-drained soil for optimal growth. It is best grown in areas with a Mediterranean climate where summers are dry and warm, and winters are moist and cool. The plant prefers full sun exposure but can tolerate partial shade. It can be propagated by seeds or cuttings.
Watering needs
Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus requires regular watering to maintain healthy growth. The plant prefers moist but well-drained soil and can withstand periods of drought. Water the plant once a week, especially during the hot summer months. Avoid overwatering, as this can lead to root rot.
Fertilization
Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus requires regular fertilization to promote healthy growth and flowering. Use a balanced granular fertilizer, such as 10-10-10, during the growing season. Apply the fertilizer every two to three weeks, starting in early spring and continuing until the end of summer. Be sure to follow the manufacturer's instructions when applying the fertilizer.
Pruning
Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus requires pruning to maintain its shape and prevent legginess. Prune the plant in late winter or early spring before new growth appears. Cut back all leggy, weak, or damaged stems to one-third of their original length. Remove any dead or diseased branches. Alternatively, you can pinch back the tips of new growth in the early summer to promote bushier growth.
Propagation of Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus
Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus is commonly propagated through seed, although root cuttings and division can also be successful methods.
Seed Propagation
For seed propagation, the seeds should be stratified before sowing to increase germination rates. Stratification involves placing the seeds in a moist substrate, such as sphagnum moss, and storing them in a cold environment for several weeks. Once stratified, the seeds can be sown directly into the ground in the fall or early spring.
It is important to note that Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus has hard seed coats that may require scarification before stratification. Scarification involves breaking or softening the seed coat to allow for water and gas exchange necessary for germination. This can be done by nicking the seed coat with a sharp knife or rubbing the seeds between sandpaper.
Root Cutting Propagation
Root cuttings can also be used to propagate Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus. Root cuttings are taken from the plant in the fall, after the leaves have dropped, and placed into a potting medium. The cuttings should be kept moist and warm until new growth emerges.
Division
Division can be done in the fall or spring by separating the root ball into sections with a sharp knife. Each section should have some roots and shoots and can be planted in a prepared site or potting medium.
Disease Management
The Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus plant is susceptible to various diseases, including:
- Anthracnose: This disease mainly affects the foliage, causing irregular tan or brown spots. Anthracnose control can be achieved through proper sanitation, such as removing infected plant residues, practicing crop rotation, and the use of fungicides.
- Bacterial Wilt: Bacterial wilt is characterized by wilting of the leaves and stems. Infected plants should be removed to prevent the spread of the disease.
- Root Rot: Root rot is caused by soil-borne fungi. Symptoms include stunted growth, yellowing of the leaves, and wilting. Proper drainage, adequate soil moisture, and crop rotation can help prevent root rot. Fungicides can also be used to suppress the disease.
Pest Management
The Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus plant is also susceptible to various pests, including:
- Aphids: Aphids are small, soft-bodied insects that feed on plant sap. They can stunt plant growth and transmit viruses. Aphids can be controlled by spraying the plant with insecticidal soap or neem oil.
- Spider Mites: Spider mites are tiny, eight-legged pests that suck sap from plants. They cause yellowing, wilting, and leaf drop. Spider mites can be controlled by increasing humidity and using insecticidal soap or neem oil.
- Thrips: Thrips are slender, winged pests that feed on leaves and flowers. They cause distorted and discolored foliage and damage the flower buds. Thrips can be controlled by using insecticidal soap or neem oil and avoiding overhead irrigation.
Regular monitoring of the Lupinus arbustus Dougl. ex Lindl. ssp. arbustus var. arbustus plant can help detect diseases and pests early, allowing for prompt management. Also, the use of cultural practices, such as proper watering and fertilization practices, can help reduce the susceptibility of the plant to diseases and pests.
