Botanical: Allium cepa, var. aggregatum
---Synonyms---The Underground Onion. Egyptian Onion.
Family: N.O. Liliaceae
The Potato Onion, also known as the Underground Onion, from its habit of increasing its bulbs beneath the surface, is very prolific. It is a valuable vegetable because it furnishes sound, tender, full-sized bulbs at midsummer, three months before the ordinary Onion crop is harvested. The bulbs are rather large, of irregular shape, from 2 to over 3 inches in diameter and about 2 inches thick. The flesh of the bulb is agreeable to the taste and of good quality. The skin is thickish and of a coppery yellow colour.
In Lindley's Treasury of Botany this Potato Onion is called the 'Egyptian Onion,' and is stated to have been introduced from Egypt about the beginning of the nineteenth century. It is much cultivated in the West of England, being quite hardy, productive, and as mild in quality as the Spanish Onion.
This variety of Onion produces no seeds and is propagated by the lateral bulbs, which it throws out underground in considerable numbers. It requires a well-worked, moderately rich soil, and is largely grown in Devon shire, where in view of the mildness of theclimate, the rule is to plant it in warm, sheltered situations in mid-winter, generally on the shortest day, with the hope of taking up the crop at mid-summer. In colder parts, however, the planting must be deferred until late winter, or early spring, yet the earlier it can be effected the better. The bulbs should be planted almost on the surface, in ground that has been previously well prepared and manured, and in rows 15 inches apart, with 6 to 10 inches space between the bulbs in the rows.
Each bulb will throw out a number of offsets all round it, which grow and develop into full-sized bulbs, which are taken up and dried when ready for pulling, and then stored for use and for future propagation. If the plants attain full maturity each bulb will produce seven or eight bulbs of various sizes. The strongest of these will in their turn produce a number of bulbs, while the weaker ones generally grow into a single, large bulb. The largest bulbs do not always keep so well as the medium-sized ones.