This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
The largest onion grown; globe-shaped, inclining to oval, light-reddish green; does not keep well; flavor very mild. This is the best variety for roasting; and, when properly cooked, makes a most savory dish. In such state, it is entirely free from the smell or taste which belongs to the other kinds, and may be eaten in reasonable quantity with impunity, by those who may have the most delicate digestion. In Portugal this sort is grown very extensively, and often, with a piece of wheaten bread, furnishes the breakfast of many of the rural peasantry. The Tripoli onion requires some little difference in the practical treatment, from what is hitherto mentioned. If possible, obtain the seeds imported from southern Europe, as they invariably produce the finest bulbs. Sow about the middle of September, and in those latitudes which are subject to severe frost, protect the young plants with glass frames during winter, in the same way as for cauliflower plants. When the severe weather is past, lift carefully, and plant singly six inches asunder, in rows twelve inches apart. Be careful to make the holes deep enough to admit the roots down perpendicularly, and do not bury the collar below the soil, but place it even with the surface.
If the weather prove dry at the time of planting, or even afterwards up to the middle of summer, copious watering will make success more certain, and add very much to size and mildness of flavor. Generally speaking, with the ordinary modes of cultivation, this sort produces only "thick necks;" that is, a preponderance of stalk and leaves, without a corresponding ripening of bulb. If, however, the advice here laid down be followed, there need be no cause for complaint on this account. During wet and cool seasons, this deficiency of ripening is occasionally prevalent in all the kinds; the which may be remedied by bending over the tops a week or two previous to usual maturity, so as to partially break the lower base, by which the developing action is arrested, and the bulbs assisted in their lateral swelling.
When the tops of any or ail of the kinds begin to ripen off, the bulbs should be immediately loosened from the soil; leave them exposed for a few days to dry, and afterwards tie them in "ropes," or spread on the floor of a dry and cool room. As they will bear almost any amount of frost without injury, there need be no care taken on this account.