"The spinach was followed by cabbage, while turnips, beets, carrots, celery, and spinach gave a second crop in the plot occupied by Gardus peas and Emperor William beans."
"Winter radishes came after telephone peas, Paris Golden celery was planted in between the hills of Stowell's blanching. The plot of early corn was sown to turnips. The hotbed was used during the late fall and winter to store some of the hardy vegetables, and the latter part of October there was placed in it some endive, escarole, celeriac, and the remaining space was filled up by transplanting leeks, chives, and parsley." (Bailey, "Principles of Vegetable Gardening," page 38.)
"If spinach is grown in frames, the sash used for one of the late crops above may be used through the following winter.
"This, like the last case, makes a total of five frames, the cost, depending on make and material, from one to five dollars; twenty sash and covers, at, say, $2.75, $55; manure at market price, calculating at least three or four loads per frame. This is a liberal estimate of space, and should allow for all ordinary loss of plants, and for discarding the weak and inferior ones. It supposes that most or all of the plants are to be transplanted once or more in the frames. Many gardeners have less equipment of glass." (Same, pages 49-50 )
Growing vegetables under glass gives smaller returns than flowers; as, for instance, a head of lettuce brings much less than a plant of carnations, and suffers more from the competition of southern crops. Nevertheless, the greenhouse-grown vegetables have come into prominence lately because they can be raised in houses that are not good enough for flowers. Lettuce and tomatoes are the principal crops; some growers raise thousands of dollars' worth each year. The greenhouse is also used for forcing plants which are afterwards transplanted to the open air. This develops them at a time when they could not grow outdoors and gives them such a start that they are very early on the market, thereby realizing the highest prices.
"Nearness to market is the most important feature in a greenhouse. In large cities, manure, which is the chief fertilizer, can be had in most cases for the hauling. The short haul is an important item, and, most important of all, the gardener who is near the market can take advantage of high prices, if the grower is near enough to the city to make two or three trips; in such a fluctuating market as New York, it is to his advantage."
Some kind of a greenhouse is necessary, but one large enough to produce a living would cost a very large sum. Vegetable raising under glass has been made profitable in special localities where nearly the whole community gives its time to building up the industry, but complete success can be attained only by having absolute control of all the conditions entering into production, and giving assiduous and undivided attention to detail.
Leonard Barron, in the Garden Magazine, says: "The best type of greenhouse for all-round purposes is unquestionably what is known as the even span—that is, a house in which the roof is in the form of an inverted V, so as to be exposed as much as possible to sunlight, and having the ridge-pole in the center. All other types of houses are modifications from the simplest form, and are designed in some way or other to fit some special requirements. These requirements may be: the cultural necessities for some particular crop; a desire to have the atmospheric conditions inside more or less abnormal at given seasons (as in a forcing house); or an adaptation to some peculiarity of the situation, as when a greenhouse is built as an adjunct to other buildings."
"It is plain common sense that the ideal greenhouse is one in which the light is most nearly that which exists outside, and in which the heat is as evenly distributed. It is practical experience that a structure with as few angles and turns m it as possible and with a minimum of woodwork in its superstructure, best answers these conditions.... Greenhouse building has developed into a special industry, and the modern American greenhouse is the highest type of construction. It is built with as careful calculation to its situation and its requirements as is the country dwellinghouse. Such a thing naturally is not cheap."
"The low-priced 'cheap greenhouse' is a makeshift of some sort. Perhaps its roof is constructed of hotbed sash, a perfectly feasible method of construction, which for ordinary, commonplace gardening will answer admirably. Or, its foundation is merely the plain earth. Such a building does admirably in the summer time, and even in the late spring and early autumn; but woe betide the enthusiastic amateur in winter, who, being possessed of one of these light greenhouse structures, has indulged in a few costly, exotic plants. They will be frozen, to a certainty! It is economy to pay a fair price in the beginning to secure a properly built greenhouse that will withstand the trials of winter."