The wild perennial lupine, or Lupinus perennis, is indigenous to most of the United States (east of the Mississippi River) and Canada. Hybridized varieties of lupine, which can be grown in your garden, come in blue, purples and reds, and tolerate most soils. They are hardy in growing zones 3 through 9. According to Fred Davis, a master gardener at Hill Gardens in Palermo, Maine: "Lupines are aphid magnets!"
Wild lupine can reach a height of up to 4 feet. They are a perennial, which means they will return to your garden each spring. Lupine grows from the same roots and the clump size increases as the plant matures. This plant has spike-like flowers that bloom in early and mid-season. If planted from a seed, the lupine will produce blooms in its second season after planting.
Hybrid Varieties of Lupine
Russell hybrids have dense spikes and bold colors. They reach a height of about 3 feet and the stems are sturdy. Minarettes are also a variety of the Russell hybrid. These plants reach a height of about 20 inches and come in a variety of colors. The Popsicle, which reaches about 18 inches, has flower spikes that are 10 inches long. These hybrid varieties do well in the garden.
Lupines develop a deep tap root that extends into the soil up to 3 feet or more. For optimum growth, the lupine should be planted in sandy, well-drained soil and in full sun. Fertilizer should only be applied in early spring. The application should be light, as the lupine requires little nutrition. Moisture requirements are average.
Lupines and Aphids
Aphids are small insects that feed on a variety of plants. In fact, there are more than 4,400 species of aphids. Aphids can be green, white, yellow, brown, red or black. You'll usually find them on the tips of plants feeding on the new growth. Aphids suck sap from the new growth of plants, where nutrients are concentrated. The sucking of the lupine's juices causes the leaves to deform. Normally, aphids don't kill the plant, but significantly damage its appearance.
Aphids and Honeydew
As the aphid feeds on the juices of the plant, they produce a sticky substance called "honeydew." Honeydew is their waste material. This material attracts bees and other insects to the plant. Black, sooty mold can also grow on the honeydew, creating an even less attractive plant.
Because these small insects increase rapidly, it's important to react quickly to an aphid infestation. Female aphids give (live) birth to other female aphids. Aphids have natural predators, such as lady bugs and lacewings, that normally keep the aphid population under control.
If aphids are on a single flower stem or two, prune the infected stems from the plant. You can also spray infested plants with a strong spray of water from your garden hose.
Other options are dusting the plants with rotenone, a pesticide, or using an insecticidal soap. Insecticidal soaps must touch the aphid to work, so be sure to spray both sides of the leaves. Many insecticides are harmful to other insects, such as lady bugs, so use your judgment when applying any insecticide or pesticide.
Always follow the manufacturer's directions when applying chemicals to plants.