This is intended as a quick guide to Alliums for those interested in identifying and growing them, particularly for seeds.

Allium schoenoprasum - Chives

Commonly grown perennial. The leaves are about 2-4mm wide, round and hollow. Flowers are usually a pinkish-mauve colour, although other colours are known.

Chives will not cross-pollinate with any other species of cultivated allium. Seed lasts up to 2 years.

Allium tuberosum – Garlic Chives

Also known as Chinese Chives. Differs from ordinary chives in that leaves are bigger, solid and flat. Flower spikes to 60cm tall with clusters of white star-shaped flowers. Perennial.

Seed viability is lost rapidly so use within 1 year. Does not cross-pollinate with any other species of cultivated allium.

Allium sativa– Garlic

Softneck garlic does not produce flower stems or flowers. Hardneck garlic produces a solid flower stem. Flowers may occur either at the end or be embedded in the stem. Hardneck garlic is sometimes called top-setting garlic. Rocambole is a form of hardneck garlic where the flower stem has a distinctive loop. When harvested and dried, hardneck garlic will have the base of the flower stem at the core of the head.

Garlic does not set viable seed. If it flowers it generally sets small bulbils that can be replanted. If black seeds form they will be infertile.

Allium ampeloprasum (Ampeloprasum Group) – Russian or Giant Garlic

Also known as Elephant garlic. This plant is more closely related to leeks than garlic. Also in this group is Pearlzwiebel (or Pearl onion).

Propagated from bulblets that form around the cloves. Does not generally produce viable seed. Unlikely to cross-pollinate with leeks even if it flowers.

Allium ampeloprasum (Porrum Group) – Leeks

This group includes the common commercial varieties as well as the Perpetual (or Multiplier) Leek.

Leeks are not day length sensitive and are biennial. Once they flower in the second season they are too tough to eat. Bulblets produce a useful sized leek faster than seed, so those varieties (such as Perpetual) are useful.

Allium cepa (Cepa Group) – Common Onion

Perennials that are usually grown as annuals. Flowers and seed develop in the second season. Onions can be distinguished from leeks and garlic by their round hollow leaves, rather than the flat strap-like leaves of leek and garlic cultivars.

Allium cepa ( Aggregatum Group) – Ever-ready Onion

Also known as Bunching or Everlasting onion. This is not commonly cultivated but is mentioned as it is sometimes confused with Welsh Onion. It is botanically a different species so can be easily distinguished if closely examined.

Allium cepa ( Aggregatum Group) – Potato Onion

Also known as Multiplier onion. These are perennial, very hardy and ready for use faster than common onion.

Only propagated from planting offsets, not seeds. Potato onions do not usually flower and if they do they are usually sterile so there is no risk of them crossing with other onions.

Allium cepa ( Aggregatum Group) – Shallots

Also known as Eschallots or French shallot. Tubular leaves are narrower than common onion or welsh onion.

Shallots are very similar to potato onions – main differences are that individual shallot leaves have their own sheath, unlike the potato onion where emerging leaves are grouped together in a sheath.

Allium cepa (Proliferum Group) – Tree Onion

Also known as Egyptian onion. Walking onion or Top-set onion. Easily identified by the bulbils that it produces instead of flowers. If flowers do occur in the flower head they never set seed and will not cross with other onion varieties.

There is also a tree onion that is a cultivar of the welsh onion. A. cepa tree onion leaves will have a semi-circular cross-section, while A. fistulosum var. viviparum tree onion will have a circular cross-section.

Allium fistulosum – Welsh Onion

Also known as Evergreen or Japanese bunching onion, Green onion, Scallion, Spring onion or Shallot.

Welsh onions can be identified by the circular cross-section of their hollow leaves and by their flowers, which open in a regular progression from the top of the umbel to the base. The only other cultivated onion that shows this characteristic in their flowers is chives.

Confusion can occur as sometimes young common onion plants are harvested and sold as spring onions, before a bulb forms.

Welsh onions have been known to cross-pollinate with common onions. Seed should be used within two years of harvest.

Keeping Seed Pure

Alliums are cross-pollinated by insect. Growing one type of chives, one of garlic chives, one of either common or welsh onion and one type of leek within a 400 metre radius should result in good seed of each. Of the varieties that do not set seed, such as potato and tree onions, seed savers can grow as many as they like knowing they will not contaminate their seed strains.

Alliums are somewhat prone to inbreeding depression so crossing between individual plants of a variety should be encouraged. It is this tendency that has led to commercial growers taking advantage of the more vigorous and productive growth of F1 hybrids and the loss of many old allium varieties.

Day Length Sensitivity

Alliums that produce a bulb are usually triggered to do so by increasing day length. Traditionally onions were thought of as being planted on the shortest day and harvested on the longest day of the year. Locations closer to the equator do not have the same variation in day length as locations in southern Australia and this affects the varieties that can be grown in tropical regions.

Onions have been bred for many different climates, locations and uses. They can be roughly categorised by whether they are short, intermediate or long day maturing, depending on the hours of sunlight per day they require to mature (11-12 hours, 12-14 hours and more than 14 hours respectively). Sometimes onions are referred to as early, mid or late varieties, where this refers to their planting time. But generally those planted early are expected to mature early and so early varieties are also short day length varieties.

Early, short day length varieties are planted in Autumn and harvested in Spring. Early onions are generally sweeter than later varieties. Examples include: Barletta, Gladalan.

Mid-season, intermediate day length varieties are planted in early winter. Examples include: Creamgold,

Late, long day length varieties are planted in late winter or even early spring. They are not harvested until Autumn and some varieties can be over-wintered in the ground without loss of flavour. Late varieties are usually good keepers as they have been bred to provide food until the spring onions are available. Examples include: Ailsa Craig, Red Brunswick.

Non-bulbing alliums such as leek, welsh onion and chives can be grown and harvested all year around.

References

Garlic and Friends : The History, Growth and Use of Edible Alliums. By Penny Woodward. Hyland House Publishing. 1996.  [Available through Bega Valley Shire Library Service]