Growing Allium (Flowering Onion)
The genus Allium (the Latin means "garlic") includes many garden plants that grow from bulbs or bulb-like rhizomes. Allium flowers form dense balls of color at the top of strong stems, and they make excellent displays in the garden or in bouquets. Allium flowers range from purple, burgundy, lilac, silvery amethyst, pink, blue, to yellow and white. Some varieties have scented blooms, but their perfume is usually pleasant and not the least oniony. The scent of the bulbs and leaves, however, may remind you of onions.
Light/Watering: Most Alliums grow best in full sun, with at least 6-8 hours of direct sun a day. Those we offer require well-drained soil and are longest lived in locations where the soil is on the dry side during summer dormancy.
Planting: Plant Alliums more shallowly than comparably sized bulbs, just one to two times the diameter of the bulb deep.
Fertilizer/Soil and pH: Alliums prefer well-drained, fertile soil. Fertilize in fall and spring with any bulb fertilizer.
Continuing Care: The leaf tips of many varieties, especially the tall ones, begin to brown before bloom time. Remove the spent flowers (except from varieties that are sterile, such as 'Globemaster') if you wish to prevent them from self-sowing.
Pests/Diseases: Alliums have few problems except when planted too shallowly or in wet soil.
Companions: Place Alliums behind heavy-foliage plants such as Peonies and Iris. Good for bedding, and in mixed borders. Flower heads are good for drying.
Dividing/Transplanting: Alliums rarely need transplanting or dividing, but this can be done when the bulbs are dormant.