The cultivations of garden lupin leave nothing to be desired in terms of color and design. With these tips for planting and care, the flower will also thrive in your garden.
Profile of garden lupin:
Scientific name: Lupinus polyphyllus
Plant family: legume family (Fabaceae)
Other names: large-leaved lupine, big-leaved lupine, many-leaved lupine, blue-pod lupine, Russell lupin
Sowing time: spring
Planting time: spring
Flowering period: June to August
Soil quality: sandy to loamy, moderately nutritious, humus rich
These information are for temperate climate!
Use in: flower beds, flower bouquets, single position, group plantin,g borders, cottage garden, flower garden, natural garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 3 (-37 °C / -35 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of garden lupin
Plant order, origin and occurrence of garden lupin
The garden lupin (Lupinus polyphyllus) is a perennial native to North America, which thrives on mountain meadows, along streams and creeks, at the edges of woods and in light forests. Already in the 19th century, the plant found its way into gardens and is considered one of the characteristic species of the cottage garden. Like all members of the legume family (Fabaceae), it has the ability to bind atmospheric nitrogen at the roots by means of symbiotic nodule bacteria, thus improving the soil. This explains its widespread distribution along road and railroad embankments, along edges and in light wooded areas. Its occurrence in nature becomes problematic when Lupinus polyphyllus penetrates into natural areas that have become rare, such as poor grassland and pasturea or wetlands, where it displaces species in need of protection. In the garden, the many cultivars, that have emerged from the wild species of lupin, enjoy great popularity as richly flowering decorative perennials.
Characteristics of garden lupin
Lupinus polyphyllus and its hybrids, anchor themselves with a tap root deep in the soil. Every spring, fresh leaves and stems sprout, which usually remain unbranched and reach a height of 60 to 120 centimeters (24 to 48 in). Stems, leaves and especially the seeds contain poisonous, bitter-tasting alkaloids.
Characteristic for the garden lupin are its fingered, blue-green and silky hairy leaves. They are alternately attached to the stems and consist of 9 to 17 lanceolate-pointed leaves.
The garden lupin usually develops flowers for the first time only in the second year. The single flower has the typical shape of plants of the papilionaceae family. There are always 50 to 80 individual flowers in terminal, grape-like inflorescences, so that the perennial decorates itself with impressive flower candles in white, violet, pink, red or yellow from the end of May to August. Some varieties and mixtures of varieties also produce bicolored flowers. Many insect species appreciate the garden lupin as a food source.
The legume, which is characteristic of the entire plant family, is slightly curved, grows up to 6 centimeters (2.4 in) long and contains four to twelve grayish, spherical seeds.
Garden lupin – cultivation and care
Garden lupin blooms most abundantly in full sunny places, but also does well in partially shady areas. Wind exposed places should be avoided, because the high heavy flower stems are sensitive to bending.
Lupinus polyphyllus prefers a medium-heavy to light soil, whose pH-value should rather be in the acidic range, because it does not tolerate lime well. It may be dry to fresh, but waterlogging can lead to root damage.
A planting in spring is to be preferred, so that the garden lupin can grow well during the season. In heavier soils, the permeability of the soil should be enhanced by adding sand. Since the perennial becomes very wide, two plants per square meter are sufficient, or simply leave about 50 centimeters (20 in) distance between the plants.
With newly planted garden lupins, one should keep an eye on the soil moisture in the first weeks and water if necessary. Later they supply themselves with their long taproots. The same applies to the nutrient supply: Additional fertilization is not necessary. High flower stems should be supported as a precaution. Pruning after the main flowering period saves the garden lupin the energy for seed formation and occasionally leads to secondary flowering.
The long taproot of the garden lupin makes a division difficult. When the perennials are exhausted, you can ensure their continued existence by reseeding.
In order to cultivate pure offspring of Lupinus polyphyllus, young basal cuttings are cut in spring. Varietal pure cultivations can be seeded directly between April and July. It is best to soak the seeds overnight in water and cover them with soil at least as thick as the seeds.
Diseases and pests
Aphids and powdery mildew can become a nuisance. Unfortunately, the fresh shoot is a feast for snails.
The garden lupin is hardy down to -37 °C / -35 °F. A layer of brushwood is not necessary, but it not only protects the plants from frosts, more likely from too much moisture.
Use in the garden
Lupinus polyphyllus works both set as a larger group and as an attractive companion plant when planted individually. It is important to use the garden lupin rather in the middle or in the background of the bed so that the gap it leaves after fading is well hidden. Pretty flowering partners are for example daisies, poppy, irises and gilliflowers, but you should always consider the coloration of the Lupinus-Polyphyllus hybrids. garden lupins are long-lasting cut flowers and low varieties are also suitable for pot planting.
Still the Lupinus-Polyphyllus hybrids belonging to the so-called “My Castle Series” of the English breeder George Russell are very popular: ‘Castle Woman’ bicolored pink and white, ‘Chandelier’ yellow and ‘Kastellan’ bicolored blue and white. If you are looking for smaller varieties, e.g. for growing in pots, you will find the Lupinus-Nanus-Russell hybrids, which grow to a height of only 50 to 60 centimeters (20 to 24 in). The new Westcountry Lupines, which are characterized by particularly strong colors and strong stems, also come from England.