Grow Allium

Allium / Ornamental Onion

Magnificent flower balls

Ornamental onions from the Allium genus are a splendid addition to the garden. The spherical flower heads rest on tall, sturdy stems. Each flower ball is composed of many small, star-shaped flowers. Allium is both easy to grow and winter-hardy. Additionally, they multiply, resulting in more flowers in the garden each year.

Allium – a large family

Allium grows wild in northern latitudes. There are also some Allium species found in South America and Africa. The genus encompasses many varieties, not just the fancy ones cultivated for their flowers but also different culinary onions. When chives or leeks bloom, their relationship to ornamental onions becomes evident.

The name “Allium” may come from the Greek word for “to avoid.” Speculation suggests that it could refer to the pungent odor of garlic, which one might want to avoid. However, we neither wish to avoid garlic in cooking nor ornamental onions in the garden!

Ornamental onions come in different heights and flower sizes, making it easy to match them with other flowers in the bed. The color range spans from purple to blue, white, and yellow. Allium looks particularly striking when grouped together, perhaps arranged by color. Alternatively, try placing individual spherical bulbs as eye-catching accents here and there in the garden.

Deer-resistant flowers

A significant advantage of growing Allium is that most varieties are shunned by both deer and rodents. Those who have witnessed their tulips being devoured in spring may be tempted to fill their flower beds with various types of ornamental onions.

Planting Allium

When you purchase Allium bulbs, either plant them right away or store them in a cool place, preferably in the refrigerator. September or October is a suitable time for planting Allium. This allows the bulbs to develop strong roots before the winter chill sets in.

Place the bulbs with the pointed side facing upward, 10-15 cm deep in the soil, depending on their size. Water thoroughly after planting.

Allium is remarkably easy to grow. The only thing to keep in mind is that, like all bulbous plants, Allium does not like to be in overly moist soil. Therefore, choose a well-drained location where water drains away. Ornamental onions thrive in abundant sunlight, but partial shade also works well. In fact, slightly less intense sun helps prolong the blooming period.

Tips: When the floral display begins, the foliage often starts to wither. Therefore, it’s smart to plant Allium alongside plants that have lush summer greenery, such as irises, hostas, or peonies.

Caring for Allium

Allium plants tolerate both cold and drought and have low maintenance requirements. Providing some nourishment in spring and fall enhances their blooming. Mulching with grass clippings or other organic material provides continuous nutrient supply to the ornamental onions.

Allium spreads both through side bulbs and by self-seeding. Consequently, you can eventually enjoy a field of ornamental onions. Once the seeds have matured, you can let them fall to the ground to get more flowers in the same spot. Alternatively, you can collect the seeds to sow them in other areas of the garden.

Ornamental onions as cut flowers

Tall-stemmed Alliums make elegant cut flowers. They stand well on their own as spheres of color in a vase. Alternatively, create a mixed bouquet where a couple of Allium flower heads hover over lower-growing flowers. Even the dried seed heads are beautiful and can be preserved as everlasting decorations.


Author: Johanna Damm

Fact-checked by Erik Hoekstra

Last updated: June 29, 2023

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