Lupinus, commonly known as lupin, lupine, or regionally bluebonnet, is a genus of plants in the legume family Fabaceae. The genus includes over 199 species, with centres of diversity in North and South America. Smaller centres occur in North Africa and the Mediterranean. They are widely cultivated, both as a food source and as ornamental plants, but are invasive to some areas.
Lupines have been cultivated for at least 2,000 years, with early cultivation by Egyptians and people in Mediterranean regions. In Bolognese tradition, lupines are believed to have attracted attention during the flight of the Holy Family into Egypt, symbolizing the fleeting nature of power and wealth.
The name “lupine” comes from the Latin word for “wolf,” due to the mistaken belief that these plants depleted soil nutrients. However, lupines actually enhance soil fertility by fixing atmospheric nitrogen.
Lupine plant varieties include hundreds of perennial and annual species. Lupines have soft green to grey-green leaves which may be coated in silvery hairs, often densely so. The leaf blades are usually palmately divided into five to 28 leaflets, or reduced to a single leaflet in a few species of the southeastern United States and eastern South America.
The plant reaches heights of up to 4 feet with spiky blooms in a variety of colors, including blue, pink, purple, white and yellow. Lupine flowers grow in U.S. Department of Agriculture plant hardiness zones 4 through 8, 9 or 10, depending on the variety.
At the end of flowering in summer, blooms left on the plant develop large seed pods, which eventually dry and burst, scattering the seeds on the soil. If you don’t want the plant to reseed itself, remove the pods before they dry. Lupine prefers to be left alone and doesn’t transplant well, as digging the plant without damaging the long tap root is nearly impossible.
Lupine flowers symbolize imagination, admiration, and a desire for new opportunities. They are also associated with resilience and positivity.
Characteristics of Lupine Flowers
- Lupine flowers grow in tall, dense spikes (racemes) of pea-shaped blooms (with an upper “banner” petal, two side “wings,” and a lower “keel” petal).
- They come in colors, including blue, purple, pink, white, yellow, and bi-colored varieties.
- The flowers are arranged in dense, cylindrical spikes or racemes that rise above the foliage.
- The leaves are palmately compound, with multiple narrow leaflets radiating from a central point, resembling fingers.
- They can be annual, biennial, or perennial plants, depending on the species.
- They bloom in late spring to early summer, providing weeks of vibrant color.
- Lupines are highly attractive to bees, butterflies, and hummingbirds, making them excellent for pollinator gardens.
- Prefer well-drained, sandy, or gravelly soils and can tolerate poor, nutrient-deficient conditions due to their nitrogen-fixing ability.
- Lupines are native to North and South America, as well as the Mediterranean region, and thrive in diverse climates.
- While many lupines are harmless, some species contain toxic alkaloids and should be handled with caution, especially around livestock.
- Lupines have the ability to fix nitrogen in the soil through a symbiotic relationship with bacteria in their root nodules, enriching the soil.
Cultivation
- Plant Lupines in a location with full sun for optimal blooms. In hotter climates, partial shade during the hottest part of the day is beneficial.
- Lupines prefer well-drained, sandy, or gravelly soil. They thrive in slightly acidic soil (pH 5.5–6.5) and are tolerant of poor soils due to their nitrogen-fixing ability.
- Sow seeds directly into the garden in early spring or fall. Scarify seeds (lightly nick the outer coat) and soak them in water for 24 hours before planting to improve germination.
- If growing indoors, start seeds 6–8 weeks before the last frost and transplant seedlings carefully to avoid disturbing roots.
- Keep the soil evenly moist, especially during the germination phase and the plant’s initial establishment. Once mature, Lupines are moderately drought-tolerant but benefit from regular watering during dry periods.
- Apply a layer of mulch around plants to retain moisture, suppress weeds, and regulate soil temperature.
- Avoid high-nitrogen fertilizers since Lupines fix their own nitrogen. Use a balanced or phosphorus-rich fertilizer if needed, particularly in nutrient-deficient soils.
- Remove spent flower spikes to encourage more blooms and prevent excessive self-seeding. Leave some seed pods if you wish to propagate them naturally.
- Cut back foliage after blooming to encourage fresh growth and maintain the plant’s appearance. Remove dead or diseased leaves as needed.
- Lupines are relatively hardy but can be affected by aphids, slugs, or powdery mildew. Ensure good air circulation, avoid overhead watering, and hand-pick pests if necessary.
- In colder regions, mulch around the base of perennials in late fall to protect the roots from freezing. For annual varieties, collect seeds for the next growing season.
Notable Species of Lupine Flower
Lupinus polyphyllus (Large-Leaved Lupine)
- Description: A popular perennial variety with tall flower spikes and a wide range of colors, including blue, pink, purple, and yellow.
- Notable Cultivars:
- Russell Hybrids: Famous for their vibrant, multi-colored flowers.
- ‘Gallery Series’: Compact plants ideal for small gardens or containers.
Lupinus texensis (Texas Bluebonnet)
- Description: The state flower of Texas, this annual species features stunning blue blooms with white tips.
- Best for: Wildflower meadows and naturalized landscapes.
Lupinus perennis (Wild Lupine)
- Description: Native to eastern North America, it has delicate blue or purple flowers and is essential for the survival of the Karner Blue Butterfly.
- Best for: Pollinator gardens and sandy soils.
Lupinus arboreus (Yellow Bush Lupine)
- Description: A woody shrub with bright yellow, fragrant flowers. Can grow up to 5 feet tall and wide.
- Best for: Coastal areas and erosion control.
Lupinus albifrons (Silver Lupine)
- Description: A perennial variety with silvery foliage and violet to blue flowers. Native to California.
- Best for: Dry, sandy soils and xeriscaping.
Lupinus succulentus (Arroyo Lupine)
- Description: An annual species with lush, green foliage and dense purple flower spikes.
- Best for: Moist, well-drained soils and wildflower gardens.
Lupinus nanus (Sky Lupine)
- Description: A low-growing annual with delicate blue flowers and a bushy habit.
- Best for: Rock gardens and naturalized settings.
Lupinus ‘Noble Maiden’
- Description: A cultivar of Lupinus polyphyllus with pure white flowers on tall, elegant spikes.
- Best for: Formal gardens or as a striking contrast in mixed borders.
Lupinus pilosus (Blue Lupine or Bluebonnet Lupine)
- Description: An annual native to the Mediterranean with soft blue flowers.
- Best for: Mediterranean-style gardens or dry, sunny areas.
Lupinus mutabilis (Pearl Lupine)
- Description: Grown for its edible seeds, it features fragrant flowers in shades of blue, purple, and white.
- Best for: Ornamental and agricultural purposes.