Alliums are a large, diverse family of plants. The allium genus contains 700 different species. We first find them in early American kitchen gardens where onions and chives were important plants to grow for culinary purposes. Today, many new forms of the original allium culinary bulbs have been hybridized into the beautiful, ornamental flowering onion plants that have so much impact in our modern gardens.
Allium bulbs of all sizes are prized as an important element in landscape design due to their versatility and multi-season bloom period. From early spring to late fall, different allium cultivars can add interest to your garden areas. In addition to their culinary assets, smaller forms of alliums make wonderful rock garden and border plants while larger forms provide dramatic accents in the garden. Look at any picture of an English cottage garden and alliums will be present.
With 700 species to choose from, there are enough alliums to suit everyone’s needs and personal color scheme. Here’s look at a few of the popular varieties.
Late spring begins the blooming period with the dramatic and popular Sensation allium. Sensation presents as large, rich purple globes on a 3- to 4-foot plant structure. Slightly later, another favorite, Gigantum, will appear on a 4-foot stem with an attractive solid purple flowerhead. Both of these alliums are often called lollipop alliums because of their long stem and round top.
In early to mid-summer, the Star of Persia or christophii allium makes its appearance. This form is short in height but large in impact. Star of Persia is only 12 to 18 inches high, but its flowerhead can be at least 10 inches in diameter with 50 or more star-shaped blossoms.
Drummer Boy allium follows with a mid-late summer display of maroon flowers on 2- to 3-inch stems. This medium size stunner spreads easily and maintains its foliage longer them many of the other alliums.
The many small alliums are especially suitable for rock gardens or the front of the border bloom throughout the season. These petite varieties come in many colors including dark purple, lavender, blue, maroon, pink, white and yellow.
Alliums of all types and sizes prefer to grow in full sun in well drained soil. To plant alliums, dig a space two to four times the width of the bulb and two to three times the diameter of the bulb to determine the depth. Fertilize with a 9-9-6 slow release fertilizer. Alliums should be planted in groups of at least three or five in the fall. Larger bulbs should be planted in the middle or the back of the garden with neighboring perennials planted in front of them to screen the unattractive foliage of the allium as it dies down. Give alliums plenty of water while they are blooming, but reduce water as they die down. Too much water will cause bulb rot problems.
Culinary alliums also have their place in our gardens as many of them produce beautiful flowers in addition to their use as food. Onions, chives and garlic chives all have showy flowers. Garlic chives are particularly useful in our fall gardens. Their tall, stately white flowers bloom for many weeks in the autumn when many other perennials are through for the year.
From their humble beginnings as a food source only, alliums have been successfully hybridized to play a major role in our current landscape design. Their versatility and long seasonal display period make them a must for our home gardens. Whether using the delicate smaller varieties in a rock garden or front border or using the highly dramatic larger plants, growing alliums will greatly enhance the overall beauty of your landscape.
• The Master Gardeners are available to answer gardening questions from 9 a.m. to noon Monday through Friday at the University of Illinois Extension DeKalb County office in the Farm Bureau Center for Agriculture, 1350 W. Prairie Drive, Sycamore. Walk-ins are welcome. For information, call 815-758-8194 or email DeKalb_mg@extension.uiuc.edu.