October is an ideal month to plant spring-flowering or Dutch bulbs. The soil will remain warm enough this fall to allow a good root system to be established and the ensuing cold temperatures of winter will supply the “chilling requirement” needed for these bulbs to flower next spring. While narcissus, tulip and hyacinth dominate the Dutch bulb market there are a number of “minor bulb” species that deserve our consideration. Even though the flowers of minor bulbs might be small, en masse they can provide a nice display of color. The tendency of these plants to flower very early makes them a welcome harbinger of spring and whets or appetite for color from spring-flowering plants whose flowers are larger and showier.
For greatest effect in the landscape these bulbs should be planted in groups and not lined out in a row. Groupings of 10 or 12 are quite common, but for the best display of color 50 or more bulbs should be used. The latter sometimes is referred to as planting in “drifts”. The bulbs should be planted fairly densely in these groupings and spaced about three inches apart. Depth of planting varies with species but, as a rule, minor bulbs should be planted about three times in depth their height.
Like most plants that produce a bulb or bulb-like storage structure (e.g. corm), the minor bulbs require a loose, well-drained soil for good growth and performance. Incorporating organic matter into the area to be planted will help improve poorly-drained soils. Alternatively, if soil is heavy bulbs may be planted in a rock garden or on raised mounds to facilitate drainage.
Crocus (Crocus species) is perhaps the best known minor bulb. The genus contains about 80 different species of which nearly 30 are cultivated. Most of the crocuses planted each fall actually are hybrids of these species and are known commercially as the Dutch hybrids. Although a bit later in flowering, the hybrids have larger, showier flowers than do the species. In all cases the cup-shaped, solitary, salver-form flowers taper off into a narrow tube. They are available in a variety of colors including yellow, white, mauve and lilac. Hybrids with striped petals also can be found. Crocus normally grow four to five inches tall and flower in late winter or early spring.
Siberian squill (Scilla siberica) produces small spikes of drooping flowers that are bright blue in color. It produces strap-like leaves about one-half inch in width and grows to a height of about six inches. Siberian squill blooms when the weather warms in spring, normally in March. Native to woodland settings, it prefers a sunny setting but can tolerate partial shade. Other species of this plant are available in other shades of blue and lavender.
Glory-of-the-snow (Chionodoxa luciliae) is also very early to flower. Like Siberian squill it bears small flowers that are blue in color. However, the centers of its flowers blend to pale blue or white and the central stamens are yellow rather than purple. It’s leaves are ribbon-like and grow up to six inches in length. Glory-of-the-snow naturalizes well in sunny areas and is usually planted in large masses for an effective display.
Snowdrop (Galanthus nivalis) is among the earliest of the spring bulbs and begins to bloom in early February in many years. The flowers are white and about an inch in diameter and droop from the flower stem held slightly above the foliage. The three inner segments of the flower bear a conspicuous green crescent at their tip. The latter is only about one-fourth of an inch in width and between four and six inches in length. When snowdrops bloom, spring cannot be too far off.
Grape hyacinth (Muscari armeniacum) bears blue flowers that resemble small urns attached to dense scapes six to nine inches in height. Its flowers are slightly scented and appear in early spring. The foliage is about one-fourth of an inch in width and up to 12 inches in length. Grape hyacinth does well full sun or partial shade and combines ideally with yellow cultivars of the larger flowered Dutch bulbs such as narcissus and tulip.
Netted (Dutch) iris (Iris reticulata) is a dwarf iris that forms true bulbs. Its flower is typical of any iris and consists of three inner segments (standards) and three outer segments (falls). Both flower and plant are quite dwarf; the latter rarely exceeds 10 inches in height. Most cultivars of this species bear blue flowers with contrasting markings on their segments. Flowers appear in late February or early March. Netted iris is an excellent choice for sunny borders or along bodies of water.
Winter aconite (Eranthis x tubergenii) produces yellow buttercup-like flowers that are held above a calyx-like involucre. They appear in late winter and early spring. Its foliage is basal in growth habit, palmately dissected, and born on long petioles. It grows to a height of only about four inches and tends to reseed itself once established. Winter aconite flourishes in full sun or partial shade but prefers cool temperatures.
The (often overlooked) minor bulbs represent and interesting addition to the garden, especially if late winter or early spring color is desired. Most of the species described here are readily available in commerce at this time of the year. Although they are planted in groupings, individual bulbs generally are not very expensive and usually are sold in packages of 10 or 12.
REVISED: July 27, 2012