Origin
Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn is a subspecies of the Lupinus arbustus, commonly known as French hybrid lupine, shrubby lupine, or dwarf lupine. It is native to western North America, from British Columbia south to California and east to Montana.
Common Names
This plant also goes by a few other common names, including pale yellow lupine, streambank lupine, and Wasatch lupine. These names help to distinguish it from other related lupine subspecies.
General Appearance
The Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn is a perennial herbaceous shrub that grows up to 1 meter tall. It has a woody stem with alternate compound leaves, with five to nine leaflets. Its flowers are pale yellow, arranged in a terminal spike, and develop into pea-like fruits. The blossoms bloom in late spring and early summer and develop into pods filled with seeds.
Uses
Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn has ecological and economic importance in its native habitat. It is a valuable species for wildlife, particularly for bees and hummingbirds, which rely on its nectar and pollen. The plant also serves as a food source for many herbivores, including elk, deer, and rabbits. Lupinus arbustus has also been used in traditional medicine to treat a range of conditions, including kidney diseases, arthritis, and respiratory ailments.
However, the plant is toxic and should not be ingested by humans or livestock without proper preparation. The seeds of some lupine species contain alkaloids that can be poisonous to livestock, causing birth defects, deformities, or even death.
Light Requirements
Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn typically requires full sun exposure for optimum growth and development. It thrives in areas that receive at least 6-8 hours of direct sunlight daily. Inadequate sunlight exposure may result in stunted growth, reduced flowering, and poor overall health.
Temperature Requirements
The plant is well adapted to growing in cool and moist environments. It prefers temperatures that range from 10°C to 24°C. When planted in warmer regions, it may struggle to thrive and may require more regular watering. Hard freezes and prolonged periods of exposure to temperatures above 28°C may cause significant damage to the plant.
Soil Requirements
The Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn prefers acidic and well-drained soils with good fertility levels. It grows best in soils with a pH range of 4.5 to 6.5. The plant parts are sensitive to excess salts and boron, thus, saline and alkaline conditions should be avoided. The addition of organic matter, such as compost and leaf litter, can help improve soil quality.
Cultivation
Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn is a hardy perennial plant that can grow in a variety of soil types. It prefers full sun to partial shade and can tolerate a range of temperatures.
For best results, plant the Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn in well-draining soil with a pH of 6.0 to 7.0. The plant grows well in USDA plant zones ranging from 4 to 8.
Watering Needs
Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn requires regular watering, especially during the growing season. The frequency of watering depends on the soil type and weather conditions.
Avoid watering the plant excessively, as it can lead to root rot. Keep the soil moist but not waterlogged. Use a drip irrigation system or a soaker hose to water the plant, as it helps to keep the foliage dry and avoid mildew problems.
Fertilization
The Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn plant benefits from regular fertilization. A balanced fertilizer with equal parts of nitrogen, phosphorus, and potassium is suitable for the plant.
Apply the fertilizer in the early spring season before new growth appears. A second application can be made in the mid-summer after the plant has finished blooming.
Pruning
Pruning the Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn plant helps to promote better growth and flowering. The ideal time to prune the plant is in the early spring season before new growth appears.
Remove any damaged, diseased, or dead foliage, branches or stems from the plant. Prune back about a third of the plant's height, leaving a few healthy buds on the stem.
Propagation of Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn
Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn, also known as Bush lupine, can be propagated through various methods. The plant has a woody stem and a deep, strong root system that help it withstand harsh weather conditions, making it relatively easy to propagate.
Seed Propagation
Seed propagation is one of the most common methods of propagating Lupinus arbustus. Collect seeds from mature pods in the fall and store them in a cool, dry place. Sow the seeds in the spring, in well-draining soil with a pH of 6-7. Place them at a depth of 1-2 inches and water them daily until germination occurs.
Cutting Propagation
Cutting propagation is another method to propagate bush lupine. Take cuttings from mature, healthy plants in late summer and early fall. Choose cuttings that are 6 inches in length and remove the lower leaves. Dip the cuttings in rooting hormone and plant them in a well-draining rooting medium. Keep the soil moist and place the cuttings in a shaded area until they've developed roots.
Division Propagation
Division propagation involves dividing the parent plant to create new plants. This method is best done in the spring when new shoots have emerged. Dig up the parent plant and use a sharp garden knife to cut it into smaller sections, making sure each section has several roots and healthy foliage. Replant the smaller sections in a well-draining soil mixture and water them regularly until they're established.
Disease Management
Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn is susceptible to several diseases, including:
- Root rot: caused by fungi such as Phytophthora and Pythium, which leads to wilting, stunting, and yellowing of the leaves. To manage root rot, avoid planting in poorly drained soils, improve soil aeration, and remove infected plants promptly.
- Powdery mildew: caused by the fungus Erysiphe cichoracearum, which forms a powdery white coating on the leaves, stems, and flowers. To control powdery mildew, use resistant cultivars, water in the morning to allow leaves to dry during the day, and apply fungicides as recommended.
- Anthracnose: caused by the fungus Colletotrichum lupini, which causes spotting on the leaves and stems, and can lead to defoliation and death. To manage anthracnose, remove infected plant debris, avoid overhead watering, and use fungicides as recommended.
Pest Management
Like many ornamental plants, Lupinus arbustus Dougl. ex Lindl. ssp. pseudoparviflorus (Rydb.) D. Dunn is vulnerable to several pests, including:
- Aphids: tiny insects that suck sap from the plant, causing distorted growth and yellowing leaves. To manage aphids, use a strong jet of water to dislodge them, introduce natural predators such as ladybugs, or use insecticidal soap or neem oil as recommended.
- Spider mites: tiny arachnids that feed on the underside of leaves, causing yellowing, stippling, and webbing. To manage spider mites, increase humidity levels around the plant, use insecticidal soap or neem oil as recommended.
- Cutworms: larvae of several moth species that cut through stems at the soil line, causing the plant to wilt and die. To manage cutworms, use collars made of cardboard or aluminum foil around the base of the plant, and apply insecticides containing Bacillus thuringiensis as recommended.
