Overview
Lupinus stinchfieldiae C.P. Sm., also known as Stinchfield lupine, is a rare and endangered species of lupine native to the United States. It is found only in limited areas of southern Oregon and northern California.
Common Names
Aside from Stinchfield lupine, the plant is also known as Stinchfield's lupine, Siskiyou Mountains lupine, and Siskiyou lupine.
Appearance
Stinchfield lupine grows up to 20 inches tall and has hairy stems, leaves, and pods. The leaves are palmately compound with 7-9 leaflets, while the flowers are bright blue-violet and can grow up to ½ inch in size. The flowers bloom in late June to early July.
Uses
Stinchfield lupine is a nitrogen-fixing plant, which means that it can contribute to soil fertility by taking nitrogen from the air and making it available to other plants. It is also an important host plant that supports the survival of endangered butterflies such as the Oregon Silverspot butterfly.
As a rare and endangered species, Stinchfield lupine is protected. It is important to conserve and protect its habitat and to avoid disturbing the plant in the wild.
Light Requirements
Lupinus stinchfieldiae C.P. Sm. requires full sun exposure for optimum growth and development. It is adapted to sunny open meadows and ridges with no shade or minimal shade, underbrush, or competition from trees.
Temperature Range
The typical temperature range for the growth of Lupinus stinchfieldiae C.P. Sm. is between 20°C - 25°C (68°F - 77°F). The plant can tolerate moderate heat and drought conditions; however, it is sensitive to extreme heat and frost conditions.
Soil Requirements
Lupinus stinchfieldiae C.P. Sm. is drought-tolerant and prefers well-drained sandy or gravelly soils with a slightly acidic pH (5.5-7.0). It can also grow well in rocky or gravelly soils with moderate fertility and low moisture. The plant does not tolerate wet soils or high amounts of organic matter in the soil.
Cultivation Methods
Lupinus stinchfieldiae C.P. Sm. prefers to grow in well-draining soil with a slightly acidic pH between 5.5 and 6.8. The best practice for planting is to sow the seed directly into the soil in autumn, in a location that receives full sunlight. The seeds need consistent moisture to germinate, and it takes about 30 days for them to sprout. This plant is drought-tolerant and does well in arid environments.
Watering Needs
While Lupinus stinchfieldiae C.P. Sm. is drought-tolerant, it does require some watering during hot, dry weather. Avoid overwatering, as it can cause root rot and damage the plant's growth. Water once or twice a week during the first year of growth, and then reduce watering to once a week when the plant establishes roots.
Fertilization
Lupinus stinchfieldiae C.P. Sm. prefers a nutrient-poor environment, so avoid fertilizing the plant in the first year of growth. After the first year, you can use a slow-release nitrogen fertilizer once a year in the spring. Over-fertilization can cause the plant to grow excessively and will affect its natural shape.
Pruning
Pruning isn't necessary for Lupinus stinchfieldiae C.P. Sm. However, you can pinch back the plant's tips when it reaches a height of 8 inches to encourage branching and bushiness. Deadheading encourages more blooms and prolongs the flowering season. Cut the flower spikes at the base of the plant once the flowers begin to fade.
Propagation of Lupinus stinchfieldiae C.P. Sm.
Lupinus stinchfieldiae C.P. Sm. is propagated by using either seeds or vegetative methods.
Propagation by Seeds:
Propagation of Lupinus stinchfieldiae C.P. Sm. by seeds is the most common method. Seedlings can be grown in containers or directly sown in their permanent location. The best time to plant seeds is in the spring after the final frost. Seeds must be scarified before planting to help them germinate. Soaking seeds in warm water for 24 hours will also help with germination.
Once prepared, seeds should be planted at a depth of about 1/4 inch in well-drained soil. Water them regularly, and they should germinate within two to four weeks. When the seedlings reach 2-3 inches tall, they can be transplanted into their permanent location, which should be an area with full sun or partial shade.
Propagation by Vegetative Methods:
Propagation of Lupinus stinchfieldiae C.P. Sm. by vegetative methods, such as stem cuttings, is also possible. Stem cuttings should be taken from the plant's basal shoots during the late spring or early summer. Cuttings should be about 3-4 inches long with at least one set of leaves and treated with rooting hormone. The cuttings should then be planted in rooting hormone and perlite mixture and kept in a humid environment with bright light, but not direct sunlight.
After six to eight weeks, rooted cuttings can be transplanted into individual containers or their permanent location. It is important to avoid damaging the delicate roots, so they should be handled carefully when transplanting into individual containers or the garden.
Disease and Pest Management for Lupinus stinchfieldiae C.P. Sm.
Lupinus stinchfieldiae C.P. Sm., also known as Stinchfield Lupine, is a rare and endangered plant species endemic to California. Just as with any plant species, it is susceptible to a variety of diseases and pests that can impact its growth and viability. Here are some common diseases and pests that might affect the plant and suggestions for managing them:
Diseases:
Bacterial Wilt: This disease is caused by the bacterium Pseudomonas syringae pv. lupini and can cause wilting of leaves, stems, and entire plants. Infected plants eventually die. The best way to manage bacterial wilt is through prevention. Avoid planting Stinchfield lupine in areas where the disease has previously been present. If bacterial wilt is suspected, promptly remove and destroy the infected plants and any nearby weeds that may host the disease.
Root Rot: This disease is caused by soil-borne fungi such as Fusarium oxysporum and Pythium spp. It can cause root discoloration, wilting, and eventual plant death. To manage root rot, it is important to maintain well-draining soil and avoid over-watering. Additionally, practicing crop rotation and avoiding planting susceptible plant species after Stinchfield lupine can help prevent the spread of root rot.
Pests:
Aphids: These small insects suck the sap from the plant's leaves, which can cause stunted plant growth, curled leaves, and yellowing. To manage aphids, consider releasing natural predators such as ladybugs and lacewings or using insecticidal soap. Insecticides should be used as a last resort and must be carefully chosen to avoid harm to other plant species and non-target organisms.
Spider Mites: These tiny insects can multiply quickly and cause leaves to appear speckled or bronzed. Severe infestations can cause plant death. Spider mites thrive in hot, dry conditions, so spraying plants with water or using a humidifier can help deter them. If an infestation occurs, use an appropriate insecticidal spray and follow the instructions carefully.
By managing diseases and pests that affect Lupinus stinchfieldiae C.P. Sm., we can help protect this endangered plant species and ensure its survival for years to come.
