The genus Scilla (Family Liliaceae) is a group of early spring perennials from Europe, Africa, and Asia with more than 100 species, of which several are grown as ornamentals. The bright blue flowers of Siberian squill (Scilla siberica) are one of the first of the spring-flowering bulbs to brighten up the landscape in early spring. Despite the name, it is not from Siberia, but from other areas of Russia and Eurasia. It is a very tough plant, however, growing in USDA zones 2 to 8. It has been cultivated since 1796.
Blooming shortly after the snow crocuses, S. siberica has nodding flowers of intense royal blue produced on arching stalks up to 6 inches long. The narrow, grass-like, dark green leaves emerge from the ground in early spring and are soon followed by the flowers. One or more flower stalks are produced from the center of the rosette of foliage. Each flower stalk supports a single flower or a raceme of 2-3 flowers.
The individual flowers are up to an inch across, with 6 blue “petals” (technically really tepals) with a single dark blue vein running down the middle and blue anthers. The bloom period is about 2 to 3 weeks long, and the flowers have a pleasant floral fragrance. They are also attractive to bees and other pollinating insects. Fortunately, unlike many other spring-flowering bulbs, they are not bothered by voles, chipmunks, rabbits, or deer. The flowers are also very tolerant of late cold snaps and will not be injured by snow or freezing temperatures.
Fertilized flowers readily form bumpy, roundish seed capsules that contain several seeds. The pods start out green, but turn brown as they mature, to eventually split to release the reddish-brown seeds. By early summer the foliage has died down, and the little round bulbs, covered in a loose dark tunic, remain dormant in the soil until the next spring.
Plant Siberian squill in masses and loose drifts for best effect. Some experts recommend “never plant fewer than 100 bulbs.” They mix well with other early bloomers, such as giant crocus, yellow winter aconite (Eranthis hyemalis), snowdrops (Galanthus spp.) striped squill (Puschkinia libanitica), light blue Glory-of-the-snow (Chionodoxa spp.), early daffodils, including ‘Tete a tete’, ‘Jetfire’, and ‘Dutch Master’, and early tulips, and Virginia bluebells (Mertensia virginica).
For those who prefer pastel colors in the garden, the bright shades of many spring-flowering tulips and daffodils can be too intense, but adding blue cools and softens the effect. And accents of bright yellow accentuates blue flowers.
They can be used in the front of beds and borders, in the herb or rock gardens, and interspersed with perennials. Plant them between later-emerging perennials, such as ferns, hostas or Lamium maculatum, so the dying bulb foliage is hidden by the other plants as they leaf out.
Although they need sun to thrive, they are particularly nice when allowed to naturalize under deciduous trees and shrubs. The trees’ leafless branches allow the sun through when the bulbs are actively growing but are starting to do dormant by the time the trees have completely leafed out.
These small, delicate beauties need to be viewed close-up, so place them along walkways and paths, or in drifts along the edge of a lawn, where their small stature and pleasant fragrance can be appreciated. Or grow them en masse for impact from a distance.
Like most bulbs, Siberian squill does best in full to partial sun and in soils with good drainage and an abundance of organic matter. In wet soils, crown rot can be a problem. Plant the small bulbs in the fall, placing them 2 to 3 inches deep and 2 to 4 inches apart. Plant in groups, preferably at the rate of 20 per square foot, instead of individually, for maximum impact in the spring. If your space is limited, or you just want to make some interesting combinations, these small bulbs can also be planted on top of deeper-planted spring bulbs, such as daffodils and tulips.
Because of the ephemeral nature of the foliage, this small bulb can easily be grown in sunny lawns. To plant Siberian squill in turf, scatter the bulbs randomly in the area you want them. Then punch or auger a hole in the sod, using a dibble or other implement (some people suggest a cordless drill with a large bit), wherever a bulb has fallen. Place the bulb (pointed side up) at the bottom of the hole and fill in with additional soil. Wait until the bulb’s foliage has started to die down in spring before resuming mowing the lawn. Also, don’t apply herbicides to the area when there is bulb foliage present – if you must treat for weeds, do that in the fall when the bulbs are dormant (and many perennial weeds are more likely to be controlled by herbicides anyway).
Because S. sibirica flowers and matures quickly – before tree leaves block out sunlight – they can be grown under deciduous trees. This species adapts readily to deciduous woodlands and where conditions suit them, they will multiply readily, both by bulb offsets and seed, to create a carpet of blue flowers. It is more likely to naturalize than many other spring-blooming flowers from bulbs. It is mainly a problem in urban areas, lawns, and degraded woodlands, and has been reported to have limited dispersal from these areas. Avoid planting this species near natural areas to avoid any potential threat.
There are only a few named varieties of Siberian squill:
- ‘Spring Beauty’ has somewhat larger flowers and sturdier stems than the species.
- ‘Alba’ is a pure white form.
- Scilla sibirica taurica has bright blue flowers.
S. sibirica is one of the best squills for forcing. Plant at least a dozen together in a pot, placing the bulbs about 2½ inches deep. Chill for about 6 weeks before bringing into warmer conditions to stimulate blooming.
– Susan Mahr, University of Wisconsin – Madison
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- Growing Hardy Bulbs – Ohio State University Extension Fact Sheet HYG-1237-98