This section is from the book "The Florists' Manual", by William Scott. Also available from Amazon: The Florist's Manual.
Plant houses, i. e., houses for raising palms, pandanus or ferns, or flowering lilies and azaleas, or growing the bulk of our bedding plants, in fact for any purpose except for roses and carnations, can run north and south. A house with its ridge running north and south with a good size of glass will give you all the light that these plants need, and in the summer when too much sun is the trouble they are not so hot.
There is no doubt that houses that are built communicating, or simply a partition wall between them, are a great saving in fuel, and in latitudes where we get great snows, and often weeks of zero weather, it is most advisable that blocks of houses be built together with only two outside walls, providing you are sure you will not want to change your business and convert them into rose or carnation houses; for this purpose they would be very unsuitable.
The conventional house of this kind is usually twenty feet wide, with a middle bench of six feet six inches, and two side benches of three feet six inches each, allowing two feet for each path and keeping the benches away from posts two or three inches on each side to avoid any drip on the plants. Whenever I speak of the width of a house as twenty or twenty-two feet, I always mean the. dimensions to be from outside to outside of posts if detached, or from center to center of posts if attached. For the general run of our plant houses the top of the posts from outside grade of ground is usually for these equal-span houses four feet six inches, with the plate on top of post and the bar about eleven feet six inches; this gives you nice headroom for the paths.
The middle bench is used for tall growing plants and the side benches for the dwarfer ones. Often the space that would be occupied by the bench is used by standing the plants on the floor or planting them out, as you do with smilax, etc. If four or five houses are used for the same kind of plants, for instance chrysanthemums, ferns, lilies, then geraniums, or maybe all palms, then there is no need of a partition wall, but unless you are in a big way of business you will find it much safer to have a partition between them. You so often want to keep one house a little warmer or cooler than others, or in fumigating you may find it very inconvenient to have to fill the whole lot with smoke when there were plants in some that you did not want to smoke.
Another style of house for general plant growing that is, I think, more economical to build and easier to work, is one of twenty-two feet. This will allow an 18-inch path against each wall, three benches a little short of five feet six inches each and two more paths one foot six inches each. The heating would be but a trifle more, the first cost of glass and bars but a fraction, and the walls and the gutters no more. In these houses the heating pipes, whether of steam or hot water, are against the walls, away from the plants, where there is no danger of encouraging red spider. Where the houses are built in this way the posts should be five feet, so as to give headroom in the outside paths. The benches in these houses could be any height to suit your plants.
It is remarkable how much we are all copyists and follow a leader. Some one breaks away from the old style, has success with his plants, and then he is copied. It is in place here to briefly review some of these changes. The first houses we remember having charge of in this country were of equal span. Then came the long-span-to-the-south house with a back wall of eight to ten feet. Excellent roses and other flowers were and still are grown in this style of house because the man in charge is excellent. These are expensive houses to build, awkward to work, and cannot be built very close together, as the rear wall of the south house will shade the house to the north. Next there was an entire reversal and the long span was put on the north, the south span being almost perpendicular. These houses could be built much nearer together, and produced fine flowers, because there was a fine grower around. Then there was a reaction with many to the old equal-span. Within five or six years there have been many blocks of houses built for roses and carnations, and some for palms containing from five or six to a dozen houses, and with no partition of any kind between them. Some of the blocks cover several acres. Now it is evident that these houses would not be suitable for plants requiring a difference of temperature. They are all right if occupied by all carnations or all roses, needing about the same heat. We have seen several such blocks and the results have been good. There are some advantages in construction and maintenance. They are certainly less costly than detached houses, are convenient and cheap to heat; the only shade is from the gutters and that little is continuously moving with the elevation of the sun. There is a great and equal diffusion of light in these connecting houses. There is still another style of house built in several places which can be any desired length and some fifty feet in width. There is no plate on the sides where the bar ends, but the bar goes down to a low wall, and where the plate ordinarily would be is a bent glass, so that there is no possible place for snow and ice to lodge. With the sole exception of this last house being .very lofty and requiring a good deal of heating power, it must be equal to a bellglass for light.
Modern Commercial Range of Connected Houses.
Ideal flowers have been produced in all these different styles of houses. The best bench of roses the writer ever saw in midwinter was in one of these blocks of connected houses, and the best carnations in an 18-foot house with two 6-foot raised benches, but that is nothing. The same growers may do as well in very different houses. The principal object sought in building for commercial growing is to get all the light possible, and the next is to build durably. Twenty years ago we built with the idea, that ten years was the life of a house. Nowadays men are willing to put more money into a house, but don't look forward to its rebuilding. And with all the woodwork of a house of good cypress and the outside walls up to the glass of cement there seems to be nothing to rot or wear out. A coat of paint is always in order both inside and out. It preserves the wood, keeps iron posts and purlins from rusting, and makes the house light, bright and good as new. It is money well spent.
Some object to painting the steam pipes. I can see no harm. They radiate just as much heat and it adds light to the house if they are on partition posts or anywhere visible. There is of late a decided dislike to building benches against a front or back wall. If the walls are upright glass the plants will get light, but they often are not, and if of posts and boards the bench, with its continual wetting from the plants on the bench, will soon rot, and if your crops should be roses or carnations you can only get to one side of them to syringe or work. Let your path be between the wall and the bench always when possible and in laying out a new house it will not only be possible but easy.