t80d 



HORTICULTURE 



September 23, 1911 



During all this time, the distance 

 between the rafters has steadily in- 

 creased, the wood members made 

 smaller and the width of the glass in- 

 creased. From glass six inches wide 

 to 24 inches is the history, although 

 for many reasons of economy, glass 16 

 inches wide has been and is generally 

 used. 



Ventilating sash are now made con- 

 tinuous instead of a number of sep- 

 arated sash. 



As the glass has increased in width, 

 so has the width of the houses, so 

 that now houses 30, 40, 55, 60 and 75 

 feet are common. Some have been built 

 over 100 feet, but it is doubtful if 

 houses as wide as this are a success 

 unless built on a slope so that the 

 roof can have sufficient slope to prop- 

 erly shed the water and not have a 

 shower on the inside as well as the 

 outside. A pitch of 32 degrees in 

 houses up to 30 feet in width is 

 preferable, and from 30 to 50 feet 2S 

 degrees have been found a good angle 

 for roofs, but 26 degrees is all right 

 for houses 50 feet and over. 

 Now as to Supports. 

 • :<_> foot houses require no columns. 

 35 ' " two columns. 



;j'J [ two columns, 



four columns. 

 !}° I four columns. 



"0 ' " six columns. 



There are several firms building 

 greenhouses in which the principle of 

 construction is to truss the roofs, 

 thus eliminating columns to a great 

 extent. This would be all right il 

 the trusses were constructed on a com- 

 pression basis, but they are con- 

 structed to a large extent on a ten- 

 sion basis and depend upon all mem- 

 bers being constantly in tune, as it 

 were. Now there is considerable 

 vibration in a greenhouse roof and 

 the constant movement is bound to 

 stretch the light rods, etc., which are 

 used in the construction. As soon as 

 one member loses its tune it puts all 

 the others out also, and I believe that a 

 greenhouse constructed on this prin- 

 ciple will deteriorate more rapidly 

 than one supported by columns or 

 with columns and compression trusses. 

 Time will tell, but if you compare two 

 houses of the same age I know that 

 the house constructed on the compres- 

 sion principle will be in better shape 

 than the one constructed on the ten- 

 sion principle. 



Semi-Iron Frame Construction. 



We have been considering what is 

 known as the iron frame greenhouse 

 construction. There is another type 

 known as pipe frame or semi-iron 

 construction. The difference between 

 the two is not very great, the differ- 

 ence being that the steel rafters are 

 omitted, the roof bars, etc., are sup- 

 ported by longitudinal purlins made 

 of pipe. These purlins are in turn 

 supported by pipe columns. The 

 painting, glazing and heating in this 

 construction are the same as in the 

 houses where rafters are used. There 

 is a slight saving in the cost of this 

 house as the steel used is less and the 

 parts require less mill work. All 

 parts both iron and wood are given 

 three coats of paint, one before ship- 

 ment, one after the framework is 

 erected and before the glass is set and 

 a finishing coat after the glass is set 

 and the other parts finished. 



The majority of houses are glazed 

 with double thick quality "A" glass in 



16 inch widths and 24 inch lengths. 

 The joints are lapped about % inch' 

 and the glass bedded in putty. The 

 use of glass 24 inches wide has been 

 quite extensive and, inquiring among 

 the florists and gardeners, the addi- 

 tional light and results obtained by 

 using glass 24 inches wide instead of 

 16 inches wide are not appreciable. It 

 seems on first thought, that there 

 must be considerable advantage and 

 lightness obtained by using the wider 

 glass, but the bars and other members 

 are so small in an up-to-date house, 

 that eliminating every other bar does 

 not appreciably increase the growing 

 qualities of a house. There are some 

 structural drawbacks to wide glass, 

 and the consensus of opinion is that 

 16 x 24 inch glass is commercially the 

 best. 



As to the Width of Houses. 

 The width and lengths of houses 

 have steadily increased until now they 

 are only governed by the length and 

 width of a man's pocketbook. Por- 

 merely, 18 and 20 feet were the most 

 popular widths, but today few growers 

 consider anything under 30 feet; 40, 50, 

 55, 60, 70 feet and so on are common. 

 Several vegetable growers have built 

 houses between 40 feet and 45 feet 

 wide and have figured out this width 

 as the most practical and economical 

 width, but others build wider ana al- 

 most each one has ideas of his own, 

 which it is the greenhouse builder's 

 pleasure to design and construct. 



Houses of the % span shape are 

 built, but not as extensively as in 

 former years. The long slope faced 

 south and consequently they were sup- 

 posed to receive a greater amount of 

 sunlight. I have seen full span and 

 % span houses built beside one an- 

 other with the same plants growing 

 in both. No difference could be ob- 

 served in the plauts and there was no 

 appreciable difference in the financial 

 returns. 



With the light construction now 

 used, I do not believe it makes any 

 difference whether a house is built 

 facing south, east or west, providing 

 there are no trees, hills or other ob- 

 jects to shade same. The topographi- 

 cal conditions of the site play an im- 

 portant part in the location, as these 

 vary in each case, and each case re- 

 quires individual consideration. 

 Ventilation. 

 Houses intended for the growing of 

 vegetables should have four lines of 

 ventilation. This is accomplished by 

 placing a line of continuous sash on 

 each side of the ridge and one line on 

 each of the vertical sides. The sash 

 are from 30 inches to 36 inches wide 

 and up. These sash are opened and 

 closed with machinery specially de- 

 signed for this purpose. There are 

 numerous types of machines on the 

 market but they all are constructed 

 on about the same principle, namely 

 a continuous shaft of pipe or steel 

 rod to which are attached arms and 

 rods which in turn are fastened to 

 the sash. A gear of the self-locking 

 design and operated by hand power is 

 arranged to turn the shaft which com- 

 municates its power to the rods and 

 arms causing the sash to open and 

 close. 



The use of solid plant beds in com- 

 mercial greenhouses is rapidly taking 

 the place of raised plant benches. 

 Many vegetable growers plant direct- 

 ly in the ground, plowing the ground 



and working the crop the same as 

 out of doors. Where beds are used 

 they are not built over 12 inches 

 above the grade and the soil confined 

 with planks or light concrete walls. 

 Heating. 

 The heating for greenhouses is cer- 

 tainly one of the most important feat- 

 ures of same. It is here that one 

 shovels his dollars into a furnace. 

 Too much attention cannot be given 

 to the installation and management 

 of the heating system. At the present 

 time there are two mediums em- 

 ployed, steam and hot water. Both 

 have advantages, but it is pretty well 

 established that heating by hot water 

 produced the best results. Hot water 

 produces a condition more like the 

 heat generated by the sun. Steam 

 gives a more intense heat. While it 

 has proved satisfactory, it is a fact 

 that the large florists are more and 

 more reverting to hot water as a heat- 

 ing medium. Whether hot water or 

 steam is used, the method of piping 

 the house is the same. If steam is 

 used, the pipes are IVi-inch, and if 

 hot water, either 2-inch or 1%-inch. 

 The pipes are placed along the sides 

 of the house hung to the side walls. 

 There should also be some pipe laid 

 through the centre of the house. Just 

 how and where to place these pipes 

 varies with the conditions to be met. 

 The number of pipes depends on 

 what temperature is required, the 

 amount of glass surface, the extreme 

 average temperature of the locality in 

 winter, the exposed or protected situ- 

 ations of the greenhouse, the good or 

 bad construction of the greenhouse it- 

 self, and many other small details 

 which are used in designing a suc- 

 cessful and economical heating sys- 

 tem. 



If steam is used, it should be a low- 

 pressure system as the wear and tear 

 on the pipes should high pressure be 

 used, would be great, to say nothing 

 of the too intense heat generated. The 

 boilers may be set in a cellar the level 

 of which is considerably below the 

 level of the greenhouse. In such a 

 case, the condensed water is returned 

 to the boilers by gravity. If the boilers 

 are on the same level as the green- 

 house a pump of some kind must be 

 used to return the condensation. 



It is the same with hot water. In a 

 hot water system, there are two ways 

 employed in generating the heat. The 

 first and one most used, is to heat the 

 water directly in a boiler and circulate 

 same through the pipes in the green- 

 house; the other, is to heat the water 

 in tanks using exhaust or live steam 

 to heat the water. In the latter case, 

 the steam passes through a coil in en- 

 closed tank, the water surrounding the 

 coil. The steam in the coil imparts 

 its heat to the water, which in turn 

 leaves the tanks, circulates through the 

 pipe returning to the tank to be again 

 heated. 



Forced Circulation. 

 There are two other methods used 

 to circulate the water, other than by 

 the gravity method. One is to have an 

 accelerator connected to the mains. 

 This devise is simply a propeller 

 turned by an engine of some kind. 

 The propeller hastens the speed at 

 which the water circulates, helps it 

 over many declivities and returns it 

 at a higher temperature to the boiler. 

 The other method is what is known as 



