December 13. 1913 



HORTICULTUEE 



81» 



VIEW IN FALL SHOW AT MINNEAPOLIS PARK CONSERVATORIES. 



best, though not exactly east and west 

 but with the southerly side facing 

 about twenty degrees east of due 

 south. This slightly eastern aspect is 

 of great importance to the rose grower 

 as his house catches the early morn- 

 ing sunshine which enables him to 

 shut oft the fire heat sooner and like- 

 wise get his syringing done at an 

 earlier hour, giving the plants a better 

 chance of drying before night; further, 

 scientists claim that the photosyn- 

 thetic effect of morning sunshine is 

 greater than that of the afternoon and 

 also that we get more sunshine in the 

 morning than we get in the afternoon, 

 all of which favors the house with an 

 aspect that is a little east of south. 

 So much for the aspect. We now come 

 to the matter of pitch or slope of the 

 roof. Theoretically the roof of a 

 greenhouse for the winter growing of 

 plants should be as nearly at a right 

 angle to the sun as possible during the 

 darkest winter months, November, De- 

 cember and January. This, of course, 

 is a counsel of perfection as there are 

 good practical reasons why it is im- 

 possible, tor oi'r houses would be too 

 high and narrow, but generally speak- 

 ing, the roof si'ould be as steep as pos- 

 sible and at the same time conform to 

 the general structural requirements. 

 For this latitude a pitch of about 

 thirty-six to forty degrees on the south 

 and fifty on the north is a very good 

 one. but the main ideas to grip are, 

 that the steener the ronf the greater 

 the amount of light which will reach 

 the plants and that as we go north a 

 steeper roof is required than would 

 be needed to give the same amount of 

 light at a point further south. A very 

 good feature of steep roofs is that the 



snow slides off them in winter es- 

 pecially where there are no gutters on 

 the house. 



Why Two-Inch' Wrought-! ron Pipes? 



Why are two-inch wrought-iron 

 pipes to be preferred to four-inch cast- 

 iron ones for heating greenhouses with 

 hot water? Because in any given num- 

 ber of feet of radiating surface we have 

 only half the quantity of water to heat. 

 This means more rapid circulation 

 and economy; then there is the fact 

 that we can more readily place two- 

 inch pipes without being in the way, 

 and there is the ease with which any 

 changes can be made and, all the 

 threads and fittings being standard, 

 repairs can be easily done. The only 

 good about the cast-iron pipe is its 

 greater freedom from corosiou; it will 

 generally last longer than the wrought- 

 iron. 



Why Must Night Temperatures Be 

 Uniform? 



Why is it more Important to keep 

 uniform temperatures at night than 

 during the day? This I conceive to 

 be a question seldom asked and per- 

 haps more seldom answered. Night 

 temperatures are such as experience 

 has shown are best suited to keep the 

 plants as inactive as possible during 

 darkness, without giving the growth 

 too much check. The optimum tem- 

 perature being given tor any kind of 

 plant, let us consider the result of 

 deviation in either direction, up or 

 down. Take any variety of the rose, 

 for instance, whose optimum tempera- 

 ture is 58 and suppose the night tem- 

 perature to be allowed to fall to 54 

 or 55 for any length of time, what will 



be the result? It will result in shorter 

 stems, fewer flowers, and if it is at 

 the critical period in the fall of the 

 year some varieties will go to sleep 

 and will be hard to awaken for a 

 month or two. On the other hand, 

 suppose the temperature be allowed to 

 run up to 62 or 63, then we get longer 

 but weaker stems and flowers which 

 will not keep so well, besides through 

 forcing the plants we lay them open 

 and make them more susceptible to 

 the attacks of all kinds of insects and 

 diseases. These ill effects are likely 

 to be more pronounced when the tem- 

 perature see-saws up and down, high 

 one night and low the next; naturally, 

 ill effects increase in proportion to the 

 amount of deviation from the correct 

 temperature. 



It has ever been my experience that, 

 other things being equal the best stock 

 was grown where they were most par- 

 ticular about keeping correct night 

 temperatures. Now, variation of day 

 temperature is not so important be- 

 cause, in the main, variations are 

 caused by the sun, and it the heat 

 runs up in bright sunshine causing 

 more rapid growth, so likewise is the 

 sun's power greater to keep pace with 

 the heat and to enable the plant leaves 

 to go through their elaborate chemical 

 operations, thereby assuring quality of 

 growth as well as quantity. 



Why Plants Turn to Light? 

 Why does a plant appear to draw 

 towards the light when growing in a 

 window? It is because light retards 

 growth, the stem on the plant grow- 

 ing in the window is shorter on the 

 side next the light and longer on the 

 side away from it, hence the lean. 



