Green Thumb – Alliums

Posted: July 14, 2021

They’re Not Just Onions Anymore

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 alliums have been hybridized into beautiful, ornamental flowering plants. Alliums are not just onions anymore!

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.

Smaller forms 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.

As spring tulips and daffodils end their bloom season, the alliums are set to begin showing off. In late spring, the 3’ to 4’ ‘Sensation’ allium appears to add drama to your garden with its large, purple globes. Slightly later, another favorite, ‘Gigantum’ bursts forth on a 4’ stem with an attractive solid purple flowerhead. Both of these alliums are often called lollipop alliums because of their long stems and round tops.

Early to mid-summer, the ‘Star of Persia’ allium makes its debut. This form is short in height but large in impact. ‘Star of Persia’ is only 12” to 18” high, but its flowerhead can be at least 10” in diameter with 50 or more star shaped blossoms.
‘Millenium’ allium was the Perennial Plant of the Year in 2018 and blooms late summer. Growing on a grass like, 12” to 18” structure, this plant produces multiple flowers that form a very compact display that lasts for several weeks.

Late summer, ‘Drummer Boy’ allium begins a display of maroon flowers. This medium size stunner spreads easily and maintains its foliage longer then many of the other alliums.

The many small, sometimes only a few inches high alliums, are especially suitable for rock gardens or borders. On a recent trip to Bishop Hill, I discovered an allium that I had never seen before. It turned out to be a nodding onion. This little charmer is native to North American and can be found growing naturally in wild areas and now in my garden as well.

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 other perennials are through for the year

Alliums of all types and sizes prefer to grow in full sun in well drained soil. Fertilize with a 9-9-6 ratio fertilizer. Allium bulbs should be planted in groups of 3 to 5 in the fall. Allium bulbs are not as common as some other bulbs so you may need to order them from catalog or internet sources.

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 season display period make them a must for our home gardens. Whether using the delicate smaller varieties or the highly dramatic larger plants, growing alliums will greatly enhance the over all beauty of your landscape.

Barb Lindholm – University of Illinois Extension, DeKalb County Master Gardener

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Photos courtesy of Bob Lindholm