Lupine flowers, also called bluebonnets, are often grown as perennial flowers for their showy, colorful spikes of flowers. Although it may take a little time to have a full, thriving garden of bluebonnets, there are a few tips you can follow to grow healthy lupine flowers yourself.
What are lupine flowers?
Lupine flowers are garden plants belonging to the pea family (Fabaceae) that bloom showy, colorful spikes of flowers. Lupine flowers can be grown as either an annual or as a short-lived perennial that grows for three to four years. These nitrogen-fixing legumes sprout brightly colored blue, white, purple, or bicolor conical inflorescences that attract pollinators like hummingbirds, bees, and butterflies.
Lupins are often used as a landscape decoration or ground cover, or even for consumption. There are around 200 species of lupine flowers, including Lupinus perennis, also known as wild lupine or blue lupine, and Lupinus texensis (also known as “Texas Bluebonnet”) is the official state flower of Texas in the United States.
When to plant lupins
Lupine wildflowers can be native to North America, and you can also plant them in containers or gardens. Lupins do best in USDA hardiness zones four through eight and should be planted in late spring or early fall for winter germination, meaning your flowers will bloom between late spring and midsummer. They can also be planted in early spring for later flowering periods.
How to grow lupins
Lupins do not transplant or divide well and are best planted from seed. However, some perennial species can be propagated by basal stem cuttings. Here is an overview of how to plant lupine flowers from a seed.
1. Soak the seeds. Lupins have hard seed coats that need a little support to germinate properly. Soak the seeds in a bowl of warm water overnight. For a cold layering method, place them in a damp paper towel in a plastic bag and refrigerate for seven days.
2. Prepare your planting site. Lupins prefer slightly acidic soil with good drainage in full sun but will tolerate partial shade. Before your seeds germinate, you should prioritize sunlight to stimulate the plant to grow. Loosen the soil about 12 to 18 inches to set your lupine to grow long taproots.
3. Sow seeds directly into the soil. Lupine seeds can be sown directly into the soil at a depth of about a quarter of an inch. Cover loosely with topsoil and water until the soil is evenly moist. Your lupine flowers will likely not bloom until the following spring, but you can cover your seedlings with a layer of mulch to keep them from drying out.
6 care tips for lupine flowers
Lupins are relatively low-maintenance flowering plants and do not require much maintenance once planted.
1. Check for pests and diseases. Adult lupins are rabbit and deer resistant, but can fall prey to aphids, pillbugs, or powdery mildew. Use an organic pesticide to take care of a large infestation.
2. Mulch your plants. Established lupins have deep roots and do not need heavy and frequent watering. Only water your established plants when the soil is rather dry and mulch around the base of the plant to retain more moisture and keep the roots cool.
3. Water your germinating seeds. While your plant is establishing, you should water it at least once a week.
4. Deadhead your flower blossoms. If you’re using your lupine plant as a hedge or border, it’s a good idea to remove faded blooms at the end of the season so your perennial lupine plant can focus on new growth. However, if you just want your lupins to keep replanting themselves, you can have them seeded and they will self-seed to bloom the following spring.
5. Avoid fertilization. Lupins fix their own nitrogen, which means they probably don’t need any additional soil amendments. Too much nitrogen will keep the foliage lush and green, but it will stunt flower spike growth.
6. Plant your tall plants. Some lupins can grow up to 4 feet tall and may require a stake for extra support. If you find your plants sagging under the weight of their buds, secure them to stakes to keep them upright.