Perennial lupine, also known as Lupinus perennis, it is a tall and lovely perennial that is native to North America, and hardy in zones 3 to 9. Lupine reaches a height of 1 to 2 feet and blossoms from April through June. Blossoms are shades of purple and deep blue, and are formed on upright spikes.
Soil and Light Requirements
Lupine will grow in most soils but prefers well-drained, loose, sandy soil. This plant has an extensive root system that depletes the nutrients of the soil yearly. Therefore, each year you will need to add additional nutrients to the soil either in the form of a time-released plant fertilizer or by the addition of compost or manure. This perennial requires full sun.
As lupine grows, it forms a clump and spreads out---thus, it is a good plant to use in borders and mass plantings, or as a focal point in your landscape design (behind or scattered among low-growing evergreens). For cottages, garden lupine is used as a background for other lower perennials, and look gorgeous growing against a fence or stone wall.
Lupine can be grown from seed. It will also self-sow if the blossoms are left to go to seed. (The soil must be loose and moist for the seeds to grow.) The seeds are rather large and have a hard outer shell. Before planting, most gardeners soak the seeds in water to allow the outer shell to soften. Other gardeners will scratch the outer shell with coarse sand paper before planting.
The lupine is an extremely easy-to-grow plant; however, they do not like to be moved. Most plants will die after being transplanted. If the lupine has spread beyond the space that you would like to see them in, remove them by digging up part of the clump of plants.
If you cut the flower spikes off after flowering, your lupine plant may produce additional blossoms in the fall. Once lupine establishes itself in your garden, you can consider it a low-maintenance plant. Watering should be done during dry periods, and a time-release fertilizer will keep it vigorous. It is rarely infested by insects or disease.