This section is from the book "The Gardener's Monthly And Horticulturist V18", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
The writer wishes it understood that he makes a distinction between growing plants under glass and forcing them. We grow, for instance, grapes in cold graperies; no gardener would call that forcing grapes. We grow a variety of plants under glass for winter-flowering, such as Roses, Carnations, Violets, Heliotropes, Bouvardias, etc, but in general we do not call that forcing. By forcing, the writer understands the using of extra artificial means to produce flowers out of their season, as Roses, Lily of Valley Hyacinths, etc, about Christmas. Undoubtedly, Mr. Grey's method, as given in a former number, is a good one for growing roses; as to the forcing of them, the writer differs with him in some points. If we want to force roses, we have first to understand why it is there is such an abundance of fine roses in March, and so few about Christmas. It is on account of the sun being more powerful in February and March. Mr. Grey speaks highly of a span-roofed house, facing east and west. At what angle the roof ought to be built, he does not mention, and that is a matter of the most importance. Flat-roofed houses are not good for growing flowers in winter.
Commercial men know the value of sunlight, as witness their troubled faces if a week of cloudy weather precedes Christmas.
If we consider all this, we come to the conclusion that it is light and sunrays that help us so much in bringing out the flowers, and we should build our houses with a steep roof - say at an angle of 55°, or more. This may seem too much to some gardeners, but let them consider how low the sun is when most needed. Houses with such roofs would be either very high or very narrow, and a hip-roof becomes necessary. The northerly roof ought by no means be steep, for the less glass on the north side the better; a warm, hollow wall would be preferable. Best quality glass should be used, and of 10x12 size, with all the wood-work as light as possible.
That light is very essential to plant-life is nothing new, and that fine colors are produced by it is also well known. Very little airing is required, for sunheat in those days is more beneficial than injurious.
A forcing-house for roses should always face South. It will bring on flowers at Christmas that would not be seen much before Easter in a span-roof facing east and west.
As to the bed manure, etc, the writer agrees with Mr. Grey, but not with his method of renewing old bushes by tying them down to the ground.
The Roses recommended by Mr. Grey can easily be kept in shape by skilful pruning, provided they are not planted too thick, a fault which is rather too often committed, the result of which is that the plants are forced to grow up too straight. The exclusion of light from the side buds causes them to break feebly and produce small buds as a consequence. As to the Marshal Niel, that is nowhere so much at home as when it can run on a trellis near the glass.
Now, as we know that roses near the glass are generally the best in size and color, let us not lay the bushes to the ground. Should it become necessary to make roses break near the ground, they might be cut in the early part of summer, when their flowers can be spared. They will then have time to make young wood before the following winter.
Thanks to Mr. Grey for bringing up this subject, and giving his method of culture.