Origin
Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus, commonly known as the bigleaf lupine, is native to western North America, ranging from Alaska to California. It can also be found in eastern Asia, Europe, and New Zealand as an invasive species.
Common Names
Aside from bigleaf lupine, this plant is also known by other common names, including Washington lupine, blue-pod lupine, and bog lupine. It is a member of the pea family (Fabaceae) and is often grown as an ornamental plant in gardens and meadows.
Uses
Among the indigenous cultures in North America, the bigleaf lupine has various uses. The plant's roots, leaves, and seeds have been used for medicine and food. The roots and seeds were ground into a powder and used for making bread, while the leaves were used for treating skin ailments, snake bites, and headaches.
Today, Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus is primarily used as a decorative plant in gardens and parks. It is also utilized for land restoration, erosion control, and nitrogen fixation purposes. The plant's ability to increase soil fertility makes it valuable for improving agricultural lands.
General Appearance
The bigleaf lupine is a perennial herb that can grow up to 1.5 meters tall. It has an erect stem that is covered in fine white hairs. The leaves are palmately compound, meaning they are composed of five to eleven leaflets. The leaves are also covered in fine hairs, giving them a silvery appearance.
The plant blooms from late spring to mid-summer, producing showy, dense flower spikes that can reach up to 40cm long. The flowers are usually blue, but they can also be pink, white, or purple, and are highly fragrant to attract pollinators. The fruit is a hairy pod containing several seeds.
Light Requirements
Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus prefers full sun to partial shade for optimal growth. It can tolerate some shade but may have reduced flowering and growth in such conditions. The plant requires at least six hours of sunlight per day to produce flowers and a healthier foliage.
Temperature Requirements
Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus has a wide range of temperature requirements. The plant typically grows well in temperatures ranging from 10 to 24°C (50-75°F). However, it can survive in temperatures ranging from -23 to 35°C (-10-95°F), but the plant might not perform optimally in those conditions.
Soil Requirements
The plant prefers well-drained soils that are fertile and rich in organic matter. It grows optimally in slightly acidic to neutral soils (pH 6.0-7.5). Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus can tolerate a range of soil types from sandy to clay, but it prefers loamy soils. The plant does not tolerate wet soils or soils with poor drainage.
Cultivation Methods
Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus, commonly known as Lupine, is a hardy perennial plant that grows well in most soil types, as long as they are well-draining. It thrives best in full sun but can also do well in part shade. Lupine can be propagated from seeds or cuttings, but seeds are the most common method of propagation.
Watering Needs
Lupine plants require regular watering to maintain healthy growth, especially during hot and dry weather. They prefer evenly moist soil, so it’s recommended to water them deeply and slowly to allow water to reach the plant's roots. It’s important to avoid over-watering Lupines as they are susceptible to root rot and fungus if kept in waterlogged soil.
Fertilization
Lupines thrive in nutrient-rich soil and thus require regular fertilization. It is best to fertilize Lupines twice a year, once in early spring and again in late summer. It’s recommended to use a balanced fertilizer with equal amounts of nitrogen, phosphorus, and potassium.
Pruning
The pruning of Lupine plants is not necessary, but it can help prolong their lifespan and promote healthy growth. It’s important to remove any diseased or dead branches as soon as possible to prevent the spread of disease. It’s also recommended to cut back the plants to their base after they have finished blooming to avoid any damage that may be caused by frost or winter weather. This will help the plant to rejuvenate and grow back stronger for the following season.
Propagation of Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus
There are two main methods of propagating Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus: seed propagation and vegetative propagation.
Seed Propagation
The most common method of propagating Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus is through seed propagation. The seeds of this plant are readily available and can be purchased from seed companies or harvested from mature plants.
To germinate, the seeds need to be stratified for a certain period of time. This process involves storing the seeds in a cool, moist place for several weeks. Once the seeds have been stratified, they can be sown directly into the garden or started indoors and transplanted outdoors after the danger of frost has passed.
It's important to note that the seeds of Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus have a hard seed coat that needs to be scarified before planting to help with the germination process. This can be done by soaking the seeds in water for 24 hours or nicking the seed coat with a knife.
Vegetative Propagation
Vegetative propagation of Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus is possible, but it's not as common as seed propagation. This method involves taking a cutting from a mature plant and planting it to create a new plant.
Softwood cuttings are taken in early summer when the plant is actively growing. The cutting should be 4-6 inches long and taken from the tip of the plant. The cutting is then dipped in rooting hormone and planted in a mixture of perlite and peat moss. It's essential to keep the cutting moist and out of direct sunlight until it roots, which typically takes a few weeks.
Division is another method of vegetative propagation that can be done in early spring or late summer. This involves digging up an established plant, dividing the root ball into smaller pieces, and replanting each piece.
Disease Management
Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus is susceptible to various fungal, viral, and bacterial diseases. The common diseases that affect this plant include:
- Anthracnose: This fungal disease causes leaf spots and can lead to defoliation. Infected plants should be removed and destroyed, and the use of fungicides may be necessary.
- Powdery Mildew: This fungal disease causes a white, powdery coating on leaves. The use of fungicides and proper plant spacing can help prevent and manage powdery mildew.
- Bacterial Wilt: This bacterial disease causes wilting and death of the plant. Infected plants should be removed and destroyed.
To manage these diseases, it is essential to maintain proper plant hygiene, avoid overcrowding, and remove infected plant parts promptly. It is also advisable to use disease-resistant varieties and proper irrigation practices.
Pest Management
Lupinus polyphyllus Lindl. ssp. polyphyllus var. polyphyllus is susceptible to pest infestations. The common pests that affect this plant include:
- Aphids: These insects are small, soft-bodied pests that suck the sap of the plant, causing stunted growth. Insecticidal soap can effectively manage aphid infestations.
- Thrips: These tiny insects feed on leaves and flowers, causing distortion and discoloration. Applying insecticidal soap or neem oil can help manage thrips infestations.
- Slugs and Snails: These pests cause damage by feeding on leaves and stems. Handpicking and using slug baits can effectively control the population of slugs and snails.
To manage pest infestations, it is essential to use integrated pest management practices, which include identifying the pest, maintaining proper plant hygiene, and selecting appropriate control measures, such as cultural, biological, or chemical methods. It is important to use chemical methods as a last resort and follow the labeled instructions for safe and effective use.
