Allium ampeloprasum is a very variable species and has been treated in various ways in the past, with many subspecies and vars being recognized. Current classification in the 'World Checklist of Selected Plant Families' (2016), treats it as one variable species, but does not recognize any subspecies or vars, Instead, it recognizes different cultivated groups of plants and, since all of these different forms, including the various cultivated forms, intergrade into each other, we are following this treatment here. We are, however, also including Babbington's Leek (Allium ampeloprasum babbingtonii) here as a separate subspecies since it is clearly distinct in its production of bulbils and therefore has a somewhat different range of uses[].

Common Name: Pearl Onion

General Information

Allium ampeloprasum Pearl Onion Group is a herbaceous, perennial plant producing 6 - 9 leaves 10 - 30cm long sheathed around a flowering scape 45 - 180cm tall, growing from an underground bulb. The bulb divides and also produces a large cluster of fairly large bulbils up to 30mm in diameter, forming in time a cluster of plants[, ].
The Pearl Onion originated in central to southern Europe and is a minor crop in several countries, especially the Nederlands, Germany and Italy. It is grown especially for the cluster of bulbils that form around the main bulb - these bulbils, which can be up to 30mm in diameter, have a sweet flavour and are used as a vegetable and are often pickled. The plant also has a range of medicinal uses (it has an action rather like a mild garlic).

Known Hazards

Although no individual reports regarding this species have been seen, there have been cases of poisoning caused by the consumption, in large quantities and by some mammals, of certain members of this genus. Dogs seem to be particularly susceptible[].

Botanical References

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Range

A cultivated form of the wild leek (Allium ampeloprasum), not known as a wild plant

Habitat

Not known in the wild.

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Bulb
Height	1.80 m
Pollinators	Bees, Insects
Cultivation Status	Cultivated

Cultivation Details

Prefers a sunny position in a light well-drained soil[]. Prefers a dry position[]. Succeeds in clay soils[]. Tolerates a pH in the range 5.2 to 8.3.
Pearl Onions can be grown as an annual crop, or be left in the ground for an extra year to grow larger. In areas where winters are generally mild, the bulbs can be planted in the late autumn or early winter, otherwise they are planted in early spring.
The bulbs should be planted fairly deeply[].
Removing the flowering head as soon as it starts to develop (or letting it grow 30cm or so tall before harvesing it for food) will usually result in more of the plant's energy going into making the bulb and therefore larger bulbs[].

Edible Uses

Bulb - raw or cooked[, , , ]. The cluster of small bulbs produced around the main bulb are the main ones used for food - they can be up to 30mm in diameter. They have a fairly sweet flavour and are often used as pickling onions or are used as a flavouring in various cooked dishes[].

Bulbils are often produced in the flower umbel. Although rather fiddly to use, these can be eaten both raw or cooked.

Leaves - raw or cooked[]. A pleasant mild to strong garlic flavour, they are available from late autumn to the spring though they can become rather tough and fibrous as they get older[].

Flowers and young flowering stems - raw. A similar flavour to the leaves, but they develop a somewhat dry texture as they mature and are then best used as a flavouring in cooked foods[].

Medicinal

This species has the same medicinal virtues as garlic, but in a much milder and less effective form[]. These virtues are as follows:-

Garlic has a very long folk history of use in a wide range of ailments, particularly ailments such as ringworm, Candida and vaginitis where its fungicidal, antiseptic, tonic and parasiticidal properties have proved of benefit[]. The plant produces inhibitory effects on gram-negative germs of the typhoid-paratyphoid-enteritis group, indeed it possesses outstanding germicidal properties[] and can keep amoebic dysentery at bay[]. It is also said to have anticancer activity[]. It has also been shown that garlic aids detoxification of chronic lead poisoning[]. Daily use of garlic in the diet has been shown to have a very beneficial effect on the body, especially the blood system and the heart. For example, demographic studies suggest that garlic is responsible for the low incidence of arteriosclerosis in areas of Italy and Spain where consumption of the bulb is heavy[]. Recent research has also indicated that garlic reduces glucose metabolism in diabetics, slows the development of arteriosclerosis and lowers the risk of further heart attacks in myocardial infarct patients[, ]. Externally, the expressed juice is an excellent antiseptic for treating wounds[].
The fresh bulb is much more effective medicinally than stored bulbs, extended storage greatly reduces the anti-bacterial action[].
The bulb is said to be anthelmintic, antiasthmatic, anticholesterolemic, antiseptic, antispasmodic, cholagogue, diaphoretic, diuretic, expectorant, febrifuge, stimulant, stings, stomachic, tonic, vasodilator[, , , , , ].

Agroforestry Uses:

Allium species usually grow well with most plants, especially roses, carrots, beet and chamomile, but they inhibit the growth of legumes[, , ]. They are, in general, bad companions for alfalfa - each species negatively affecting the other[].
Members of this genus are rarely if ever troubled by browsing deer[].

Other Uses

Although no specific mention has been seen for this species, the juice of most species in this genus (especially those with a strong onion or garlic smell) can be used as a moth repellent[].
The whole plant is said to repel insects and moles[].

Propagation

Seed - this form of Allium ampeloprasum is usually propagated by dividing the bulbs, or planting the bulbils. However it can also be grown from seed, though the plants produced will be variable in the size of their bulbils.
The seed is best sown as soon as it is ripe in a cold frame, though it can also be sown in a cold frame in the spring[]. Prick out the seedlings into individual pots when they are large enough to handle. Well-grown plants can be planted out into their final positions in late summer or the autumn, otherwise grow them on for a further year in pots and plant them out the following summer.
Division in late summer or early autumn. Dig up the bulbs when the plants are dormant and divide them into their individual cloves. They are best replanted immediately, either in the open ground or in pots in a cold frame, though they will also store for some months (preferably only divide the bulbs when you are ready to replant the cloves).
There is usually a cluster of bulblets produced at the base of the larger bulb. These can be replanted immediately, or stored and replanted in the spring, They produce a crop by the end of the next growing season.