Grape hyacinths are spring-blooming bulbs noted for their reliable flowering and easy care. Grape hyacinths grow in U.S. Department of Agriculture hardiness zones 3 through 8. Called grape hyacinths for their grapelike flower clusters, these bulbs are winter-hardy. After they bloom, leave grape hyacinths in the ground or dig them up and divide for more plants.
Grape hyacinths bloom on flower spikes among narrow, floppy leaves. In spring, leaves sprout from the bulbs and grow up to 8 inches high. One to three flower spikes emerge from the centre of the leaves and open into bell-shaped white, lavender or blue florets. The florets, growing like upside-down grape clusters, bloom for three to six weeks. Select bulbs for autumn planting. The bulbs need well-drained soil, but grow in sun or partial shade. The first leaves push up through cold ground and often sprout through snow.
When flowers die back, foliage continues to absorb nutrients for the bulbs and then dies back. Bulbs left in the ground often sprout new leaves in late autumn. These second-growth leaves frequently remain green until spring. Leave your grape hyacinth bulbs in place, and they will gradually spread in masses and flowering waves across the ground. They partner well with other bulbs such as regular hyacinths, daffodils and crocus for early spring colour.
After grape hyacinths bloom, divide them as desired for rejuvenation or more plants. Left undisturbed, the bulbs continue to grow by producing small and large bulbs that crowd into adjacent soil. When the bulbs are overcrowded, they cannot reach ground nutrients and produce sparse foliage with few flowers. Dig the bulbs up after blooming, discard the smallest or soft bulbs and replant the larger, firm bulbs about 3 inches apart. This renews the bulb bed for better foliage and more profuse flowers. Dig up extra bulbs and plant them among other bulbs, shrubs or perennials for spring colour.
Grape hyacinths need small spaces for large yield. Plant them in borders, massed under trees or along building foundations. Use 50 or more bulbs for colour masses, or mix them as spring colour around later-blooming perennial shrubs. The hardy bulbs grow easily in containers or planters mixed with miniature bulbs and spring flowers. Their long-lasting blooms add colour as walkway edging. Use them as accent flowers in rock gardens as the small bulbs fit easily into small spaces and spread wherever they find soil. Because they can remain in the ground after flowering, they are well-suited to irregular slopes or in ground covers that are not regularly manicured.