By: Mary H. Dyer, Credentialed Garden Writer
Also known as Coulter’s lupine, desert lupine (Lupinus sparsiflorus) is a wildflower that grows across the southwestern United States and parts of northern Mexico. This nectar-rich desert wildflower is highly attractive to a number of pollinators, including honeybees and bumblebees. Read on to learn more about desert lupine plants.
A member of the pea family, desert lupine is a distinctive plant with dark green, palmate leaves and spikes of blue or purple, pea-like flowers. Height at maturity is about 18 inches (45 cm.), but desert lupine may reach heights of up to 4 feet (1 m.).
Desert lupine plants bloom prolifically in moist years, carpeting the desert with color. However, this hardy plant blooms even in dry years, and is commonly found growing along roadsides.
Well-drained soil is a necessity for growing desert lupines; don’t expect the plant to thrive in clay. Full sunlight is preferable, however, the plant will tolerate light shade, which can be beneficial during hot afternoons.
Plant desert lupine seeds directly outdoors in fall or plant stratified seeds in early spring. Before planting, rub the seeds lightly with sandpaper to break through the hard outer coating. You can also soak the seeds in warm water overnight.
Loosen the soil before planting to allow space for the long taproot, then cover the seeds with about ½ inch of soil (1 cm.). Water as needed to keep the soil lightly moist until the seeds have germinated.
Plant desert lupine seeds where you expect them to live out their lives. Desert lupine plants don’t appreciate having their roots disturbed and don’t transplant well.
Desert lupine seedlings tend to be slow growers. Water the plants lightly as needed and protect them from frost.
Once desert lupine plants are mature, they tolerate drought well. However, they benefit from occasional irrigation during dry weather.
Feed desert lupines lightly once per month during the growing season using a general-purpose fertilizer. Like other lupine plants, they fix nitrogen in the soil, making them good companions wherever nitrogen loving plants will be grown.
Pinch wilted flowers to encourage prolific blooming throughout the season.
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Lupines grow wild across much of the U.S., creating blankets of color in early summer. Wild lupine ranges from white and pink, to shades of blue and purple. Cultivated varieties introduce yellow, orange, red and salmon to the garden bed. Blooming on tall spikes, lupine gives the illusion of a spiral of tiny blooms that tapers to a point at the top. Propagating lupine from seed is relatively easy, but should not be attempted from hybrid varieties. Hybrids do not reproduce true to form and may produce inferior plants.
Choose healthy, vigorous plants for seed production. Seeds carry the genetic makeup of the plant and typically produce characteristics of the parent plant. Consider blooming time, size and color when selecting plants to produce seeds.
Allow lupines to bloom and set seed. Deadheading to remove faded blooms prevents the plant from forming seeds.
Check the seeds when the pods yellow and turn brown. Lupine pods look like small pea pods and produce a row of tiny white seeds that turn dark brown or black when mature. Open the pod with your fingers. If seeds are hard and dark, it is time to harvest the pods.
Harvest the seedpods on a cool, dry day after the dew has dried on the plants. Snip or pick the pods from the plant.
Open the pods and remove the seeds.
Spread seeds on a newspaper or paper towel and allow to dry completely for two to three days to remove any excess moisture.
Place seeds in a sealed envelope. Mark the date and the type of seed. Store the envelope in glass jar or airtight container to prevent damage from moisture or insects.
Lupine seeds require cold stratification before planting in spring. Place seeds in the refrigerator for four to six weeks before planting.
Starting lupines indoors increases their rate of survival and allows you to germinate them at a time that is convenient for you. Nick each seed with a razor before refrigerating the seeds for a week or longer, and then plant them in moist, lime-free potting mix. Keep the soil moist, and place the pots in a location that receives at least eight to 10 hours of direct sun each day. If sunlight is unavailable, supplement with an artificial full spectrum, or “grow,” light. Transplant the seedlings outdoors or to very tall pots when they reach 2 to 3 inches in height, because older plants cannot be reliably moved.
Lupines can only be transplanted successfully when they are very young due to their long, fragile taproots. Specimens grown in peat pots survive better than those removed from traditional clay or plastic pots, because the root receives less handling. To transplant lupines outside, place them outdoors for a week during the spring months to accustom them to your local climate. Dig a hole 1 1/2 times deeper than the height of the pot and place the seedling so that the crownlike structure from which the leaves grow remains above ground.