A number of hybridized varieties of wild perennial lupine exist (like Russell, Minarettes and Popsicle), and come in many colors--blue, purple, yellow, red, pink and bi-color. The wild perennial lupine is hardy in USDA hardiness zones 3 through 9. Lupines prefer well-drained, sandy soil with a pH of 6.8 to 7.2.
This flowering perennial has spike-like flowers, which blossom in early summer. Plant size depends upon the cultivar: Russell hybrids reach a height of 3 feet, Minarettes reach a height of 20 inches, and the Popsicle variety gets 18 inches high. Lupines grow in a clump; several stems grow out of each individual clump. They develop a deep tap root as part of their root system. This tap root can grow up to 3 feet or more into the soil. Lupines do well when planted in full sun. They do not require a lot of nutrition, and will only need light fertilization, which should be applied in early spring.
The pH of the soil tells you what the acidity or alkalinity of the soil is; there is a standard pH scale, which ranges from a pH of 0 to a pH of 14. The neutral point on this scale is 7. According to the State University of New York, as the amount of hydrogen ions in the soil increase the soil pH decreases, making the soil more acidic. So the soil becomes more acidic the more the number decreases below 7; when it is going from a pH of 7 up to 14, the soil is becoming more alkaline/neutral.
How pH Affects Plants
Plants receive the majority of their nutrients from the soil they are grown in. Nutrients are first dissolved in the soil; plants can then take these nutrients in through their root systems. Acidic soil provides more solubility for these minerals and nutrients (as opposed to a more neutral or alkaline soil). Therefore, the most desirable pH is one that would be able to provide the plant with readily available nutrients. This is generally a pH of from 6 to 7, according to the State University of New York. (Lupines prefer soil with a pH of 6.8 and 7.2.)
Measuring Soil pH
The soil can be tested by using a pH meter or a testing kit, which uses a dye to indicate the pH of the soil. The dye/chemical is applied to the soil sample, and then the color of the soil is compared to the color chart provided. The color indicates the approximate pH of the soil. Most garden centers have pH soil-testing kits available for purchase. Soil samples can also be sent to most local universities for testing.
Soil pH requirements vary from plant to plant. Many plants tolerate and thrive in very acidic soils, such as azaleas, rhododendrons and blueberries. Lupines prefer a slightly acidic, sandy soil.