This clumping, long-lasting perennial spreads from rhizomatous roots and has dark-green heart-shaped leaves. Small blue flowers with white centers rise on stems in spring. The bloom period lasts for about four weeks. Although Siberian bugloss is a slow grower, the species will eventually spread out and make a nice ground cover. The flashier variegated varieties are a bit slower to fill out yet provide interest and color all season. Siberian bugloss is generally planted from potted nursery plants in early spring, as soon as the ground can be worked. Siberian bugloss is often planted in shade gardens, woodland settings, and near ponds. It can make a great ground cover and looks beautiful lining a path or border, although it can take a while to fill in. Since deer do not often bother this plant, it makes a nice alternative to hostas. Companions with different textures and leaf shapes include hellebores, iris, hostas, bleeding heart, geraniums, and even late-blooming daffodils.
Light
Siberian bugloss prefers shady conditions, though it can survive in full sun if it gets more moisture. The variegated leaves can easily burn in direct sunlight and plants may go dormant in extremely sunny conditions.
Soil
This plant is not too particular about soil pH, but it does like rich, moist soil. Lots of organic matter and organic mulch will help it become established quickly and keep it growing well. Siberian bugloss does not tolerate dry soils.
Water
Keep new plants well watered. While Siberian bugloss plants prefer constant moisture, they will become more drought-tolerant once they are established. Mulching will help maintain the cool, moist soil that Brunnera prefers.
Temperature and Humidity
Though rated for hardiness zones 3 to 8, Siberian bugloss prefers regions with cool summers. You may have trouble with it in zones that have especially hot and humid summer conditions (zones 7 to 8).
Fertilizer
These plants prefer rich soil but do not require supplemental feeding, as long as the soil is not too poor or dry.
Types of Siberian Bugloss
The species form of Brunnera macrophylla, with solid green leaves, is readily available. It has lovely sprays of blue flowers and is an extremely tough plant. In addition, there are several cultivars available:
‘Diane’s Gold’ has golden-yellow leaves and blue flowers.‘Hadspen Cream’ has extra-large leaves with irregular white outer margins.‘Jack Frost’ is a patented cultivar with wilvery leaves with green veins.‘Langtrees’ (aka ‘Silver Spot’) is a very hardy plant with leaves that are dotted with silver.‘Looking Glass’ has silver leaves that look almost metallic.‘Queen of Hearts’ is an updated version of ‘Jack Frost’, this cultivar boasts larger, bolder silvery leaves.‘Alexander’s Great’ boasts jumbo-sized dark green leaves veined in silvery-white.
Pruning
If the foliage starts to look unsightly during the summer, cut remove them to encourage new leaves to fill in. If you do not want your plants to self-seed (Siberian bugloss easily reseeds itself), deadhead as the flowers start to fade. Don’t cut the whole plant back to the ground in the fall—the leaves will help protect the crown during winter and you can easily clean away the old foliage in the spring when the new leaves begin to emerge.
Propagating Siberian Bugloss
The best means of propagation is to simply dig up an established clump in early spring, divide it into healthy segments, and replant. Siberian bugloss can be short-lived, and dividing your plants every three to five years will keep them around longer. Keep in mind that some varieties are protected by a plant patent and their propagation is prohibited.
Growing Siberian Bugloss from Seed
Although the plant may self-seed, the volunteers from cultivars usually do not grow true to the parent plant and are best weeded out if you want to preserve the look of the parent. For example, volunteer seedlings of variegated plants often have solid green leaves. Therefore it is not recommended to grow it from seeds that you have collected yourself, and seeds are not commonly available from seed companies.
Potting and Repotting
This plant can be a great choice for containers that are placed in partial or full shade. The variegated leaf varieties will make a nice filler throughout the season. Use a pot that is large enough to accommodate the root system, plus a couple of inches to allow for growth. Make sure the container has large drain holes. Fill the pot with a quality potting mix, which usually comes with slow-release fertilizer. Like all container plants, Siberian bugloss needs more watering when grown in containers. When the roots grow out of the drain holes, or the plant becomes root-bound, it’s time to transplant it to a larger pot.
Overwintering
All plants, whether planted in garden soil or in containers, benefit from a thick layer of mulch during the winter months. Siberian bugloss is a hardy plant and winterization is only required when you are growing it in containers because the winter freeze can kill the roots. In climates with extended winter frosts, cover the container with a double layer of burlap and bubble wrap.
Common Pests & Plant Diseases
Since Siberian bugloss prefers cool, moist shade, slugs may become a problem, but varieties with thicker leaves are rarely bothered. Otherwise, Siberian bugloss free of serious pests and diseases.
How to Get Siberian Bugloss to Bloom
Failure to bloom may be due to too much sunlight, which causes the plant to go dormant prematurely.
