Soil and Cultivation.—The Onion requires a light, loamy, mellow soil; and, unlike most kinds of garden or field vegetables, succeeds well when cultivated on the same land for successive years. With the exception of the Top and the Potato Onion, all the varieties are raised from seed. Previous to sowing, the ground should be thoroughly spaded over or deeply ploughed, and the surface made smooth and even. The seed should be sown as early in spring as the soil may be in good working condition. Sow in drills fourteen inches apart, and half an inch in depth. When the plants are three or four inches high, thin them to two inches asunder; and, in the process of culture, be careful not to stir the soil too deeply, or to collect it about the growing bulbs. The onions will ripen in August, or early in September; and their full maturity will be indicated by the perfect decay of the leaves, or tops. The bulbs may be drawn from the drills by the hand, or by the use of a common garden-rake. After being exposed for a few days to the sun for drying, they will be ready for storing or the market.
Preservation.—The essentials for the preservation of the bulbs are a low temperature, freedom from frost, dryness, and thorough ventilation.
Seed.—For the production of seed, select the ripest, firmest, and best-formed bulbs; and, in April, transplant them to lines two feet and a half or three feet distant, and from nine to twelve inches apart in the lines, sinking the crowns just below the surface of the ground. As the plants advance in height, tie them to stakes for support. The seeds ripen in August: and the heads, or umbels, should be cut off when they assume a brown color; for then the capsules begin to open, and shed their seeds. After being threshed out, the seed should be exposed to the action of the sun until it is thoroughly dried; for, when stored in a damp state, it is extremely liable to generate heat, and consequently to lose its vitality.
Varieties.—Few of the numerous varieties are cultivated to any extent in this country. Many of the kinds succeed only in warm latitudes, and others are comparatively unimportant. The Danvers, Large Red, Silver-skin, and the Yellow seem peculiarly adapted to our soil and climate. The annual product of these varieties greatly exceeds that of all the other sorts combined.
Blood-Red. Thomp.
French Blood-red. Dutch Blood-red. St. Thomas.
Bulb middle-sized, or rather large, flattened; skin dull red,—the coating next within glossy, and very dark red. The internal layers are palest at the base; and, except at the top, are only colored on their outsides. Each layer is paler than the one which surrounds it; till the centre is reached, which is white.
It is a good keeper, but one of the strongest flavored of all varieties. It imparts to soups, or other dishes of which it may be an ingredient, a brownish or blackish color.
Brown Portugal. Thomp.
Brown Spanish. Cambrai. Oporto.