Zone 5 of the USDA agricultural hardiness map shows a narrow swath of the country stretching mainly from the Rocky Mountains to the East Coast. This zone experiences a minimum winter temperature of negative 20 degrees F. Selecting bulbs to plant in the fall in this zone requires knowing what bulbs will survive the winter and flourish in the spring. Bulbs for fall planting should be planted early enough to establish themselves, generally a month or more before the ground freezes.
These showy flowers are perhaps the best known of the fall planted bulbs. By selecting early, mid-season and late-blooming varieties, a full two months of flowers can be had. Planted in masses and clumps, they provide bursts of color that fade after one to two weeks. Plant bulbs 6 to 9 inches deep, spaced 3 inches apart. Different varieties have different requirements.
The harbinger of spring, the tiny and delicate crocus often pushes its way through the snow to be the first to bloom. Tiny grasslike leaves emerge first, followed by an almost too-large flower atop a slender stalk. Crocus will self-sow if left alone, and may be used to naturalize a lawn, providing flowers even before the grass greens in the spring. Set bulbs 2 to 3 inches deep in small groups, and watch them spread.
Daffodil and Jonquil
These members of the narcissus family follow the crocus and precede the tulip with their showy blooms of yellow, white, peach, pink or chartreuse. Some grow a single flower per stem, others several. Most varieties do best planted 6 to 8 inches deep. In the spring after the blossoms have fallen, leave the leaves and stems intact while the plant rejuvenates itself. Once the leaves yellow and fall, remove them.
Frequently referred to as muscari, the grape hyacinth is another early-to-mid-spring bloomer. The tiny bulbs should be planted about 2 inches deep in masses. Muscari have thick, grasslike leaves and purple, cylindrical flower heads consisting of many flowers that reach a height of about 5 inches. Left alone, the grape hyacinth will self-seed and, at the same time, produce offsets of its bulbs. Plant these bulbs in early fall for the best spring showing.
As crocus herald the new spring, snowdrops may just be fading. They prefer the cold, and bloom in late winter or very early spring. These members of the amaryllis family grow to 8 inches tall and are pure white. Set them 3 inches deep in well-drained humus as a mass planting. They do well in rock gardens and woodland settings, but poorly in containers. Divide and replant snowdrops every other year; overcrowded bulbs will not flower.