ONION, the Common, or Allium Cepa, L. an exotic plant, probably originating from Asia.
There are several varieties of the common onion, the principal of which are known by the names of Strasburgh, Spanish, and Egyptian. They are propagated by seed, which ought to be sown towards the end of February, or early in March, during dry weather; in the proportion of six pounds per acre, on light rich land, that has previously been well dug, levelled, and cleared from all weeds. In the course of five or six weeks, the onions will appear above ground; and, after growing a month, they will, in a good soil, admit of being hoed; wWch operation must be performed with a small implement, not exceeding 212 inches in breadth; and it will also be necessary to remove such as may stand too closely together, so as to leave the rest about three inches asunder. At the expiration of another month, the hoeing ought to be repeated, and the plants left four or five inches apart: in the course of six weeks, the hoe is once more employed; the weeds are carefully removed; and the onions suffered to grow only at the distance of six inches square; by which means they will attain a very large size.
Should the weather continue dry, the operations before stated, will be sufficient, till the onions are ready to be pulled; but, if the season prove damp, and weeds vegetate luxuriantly, they must be removed by the hand; because, after the onions have begun to bulb, it would be improper to stir them with a hoe.—Towards the middle or latter end of August, they generally cease to grow; a circumstance which may be ascertained by the shrinking of their blades: it will, therefore, now be necessary to draw them out of the earth, to cut off the tops of the blades, and to dry them, either in a warm place, or by exposing the bulbs to the sun; and turning them every second day, lest they should bud, as often happens in damp weather.—This mode of cultivation is applicable to Leeks, on the properties of which we have already treated, in their alphabetical order.
Beside the varieties above-mentioned, there is another, denominated Welch Onions, which are cultivated only for spring salad; as they form no bulbs.—These are sown towards the end of July; and in the course of a fortnight appear above the ground; but in October their blades perish, and do not revive till January; when they shoot up vigorously; so that, in the month of March, the plants will be fit for the table.
The properties of onions in no respect differ from those of garlic, excepting that the former are less pungent (see vol. ii. p. 366), and are, therefore, more generally used for culinary purposes. Many persons, however, dislike them on account of the strong and disagreeable smell which they communicate to the breath: but this inconvenience may be obviated by eating a few raw leaves of parsley, immediately after partaking of onions, the scent of which is thus completely removed, and they are at the same time rendered more easy of digestion.
Onions were formerly reputed to be an efficacious remedy for suppressions of urine, and in dropsical complaints; but they are at present chiefly used in external applications, such as poultices, or cataplasms for suppurating tumors, &c.—A distilled water from these roots is frequently recommended on the Continent, as an excellent solvent of the stone and gravel.