Allium (Alliaceae)

The Allium genus is large, comprising approximately 700 species , plus a similar number of cultivars. Alliums are native to the temperate regions of the Northern Hemisphere .

In the kitchen, different types are used as vegetables or herbs, such as:

• onion

• shallot

• leek

• chives

• garlic

The largest group, however, consists of ornamental onions , which are used in gardens. Some varieties are suitable for naturalizing among shrubs and under trees, while others stand out with their blooms in sunny borders or are suitable for rock gardens and pots.

Properties of ornamental onions

A disadvantage of many ornamental onions is that the leaves turn yellow before the flower has fully developed . Therefore, they are often planted behind or between perennials to hide the wilting leaves.

Tall cultivars are suitable as cut flowers . The inflorescence lasts a long time in a vase, but if the water isn't changed regularly, it can develop a strong odor (especially in warm weather). All allium species have a characteristic onion aroma .

The inflorescence consists of star-, bell- or saucer-shaped flowers that together form a spherical or oval inflorescence on a bare flower stem.

Most alliums are bulbous plants ; some have a thickened root (like leeks). The bulbs can be propagated from seed or by removing bulbils. Other species are propagated from seed or by division.

Caution: Touching the bulbs may cause skin irritation in some people.

Location and soil

Most ornamental onions like well-drained soil , preferably with little humus, and a sunny spot .

Plant ornamental onions in late autumn . On poor soil, some well-rotted manure can be added. Fresh manure or chicken manure is unsuitable —onions don't tolerate it well.

Planting depth is generally equal to the height of the bulb. Small bulbs can remain in the ground and often naturalize well. Large bulbs should usually be lifted after the second year and stored at 25°C, after which they should be replanted in November—in a different location to prevent disease.

Well-known Allium species

Allium cowanii

• Flowering: April-May

• White flowers in airy umbels

• Thin stem, good cut flower

• Closely related to Allium neapolitanum

• Good among low grasses for a natural look

Allium gladiator

• Height: up to 140 cm

• Spherical flowering in May-June

• Star-shaped flowers, light purple to pink

• Good cut flower

• Cross between A. aflatunense and A. macleanii

Allium karataviense

• Compact growth habit

• Height: 10–25 cm

• Gray-green leaves stay beautiful for a long time

• Spherical flower with 50+ pink-white flowers with a purple stripe

• Suitable for rock garden or pot

• Cultivar 'Album' blooms white

Allium moly (Golden garlic)

• Yellow flowers, star-shaped

• Height: 15–24 cm

• Remains decorative for a long time

• Tolerates sun and partial shade

• Grows wild well

• Origin: Southwestern France and eastern Spain

• Cultivar 'Jeannine' produces two flower stems per bulb

Allium 'Mount Everest'

• Height: approx. 120 cm

• White, star-shaped flowers, inflorescence approx. 15 cm in diameter

• Stays green for a long time

• Good cut flower

• One of the few white-flowering large-flowered varieties

Allium schubertii

• Unique, explosive inflorescence (diameter up to 30–40 cm)

• Lilac-purple with light accents, pink stems

• Leaves wilt quickly

• Flowering: June

• Good cut flower, also suitable for drying

• Sensitive to frost → protect with winter cover

Allium sphaerocephalon (Drumstick)

• Origin: Central and Southern Europe

• Flowering: June–July

• Compact, oval flower cluster on a 70 cm high stem

• Changes color from green to reddish purple

• Suitable for borders, naturalising in lawns

• Recommended to plant in groups for visual effect

• Good cut flower, also sold as 'drumstick'