GREENERIA FULIGINEA 399 



GREENHOUSE 



GREENE RIA FULJGI NEA. A fungus causing " bitter- 

 rot " on grapes. 



GREEN FLY. See APHIDES. 

 GREENGAGE. A dessert plum. 

 GREENHEART. Necta'ndra Rodice'i. 



GREENHOUSE. This is a light, airy structure de- 

 signed for plants which can sustain a lowish temperature, 

 but cannot withstand the vicissitudes from frost to sun- 

 shine, and from damp to dry, of our common winters. 

 It is distinguished from a plant-stove in requiring but 

 little artificial heat ; and from a conservatory in having 

 all the plants (with, perhaps, the exception of climbers 

 for the rafters) grown in portable pots or tubs, and these 

 generally set upon a stage to bring them nearer the glass. 



The mode of constructing such a house must be regulated 

 by the wishes of the proprietor, and the conveniences at 

 his disposal. For general purposes any aspect will do 

 in an emergency, except the north, and that might be 

 selected for those plants that delight in the shade. The 

 more command of light, with the means at hand of 

 reducing its fierceness and heat when too powerful, the 

 better. From due south to south-east and south-west 

 may be considered the best aspects. If it is a lean-to 

 house, having a sloping roof from a back wall, it should 

 always have a considerable amount of upright glass in 

 front to receive the oblique rays of the sun in winter. 

 By the side of a cottage ornte the front of the house may 

 thus partake of the same style of architecture, while 

 the shed-like, sloping roof may be exchanged for a ridge- 

 and-furrow one, and that concealed from external obser- 

 vation by a light entablature or frieze work. For a neat 

 detached structure it should stand, less or more, north 

 and south, have a ridge-and-furrow roof, and means for 

 breaking the sun's rays in the morning and afternoon. 

 We are supposing it to be glass all round. When in 

 connection with other buildings a very useful and elegant 

 house is formed, having the front and ends of glass, a 

 hipped roof, and an opaque back wall. Here, likewise, 

 by an ornamental entablature, the roof, if desirable, may 

 be wholly or partially concealed, so as not to interfere 

 with architectural propriety, though we should have no 

 great scruples on this score, as the utility of an object, 

 if apparent, gives its appropriateness. 



The size of the glass to be used must depend upon the 

 taste and the money wished to be spent by the proprietor. 

 For the roof, especially, it will be desirable to have it 

 at least sixteen ounces to the foot. Small squares can 

 be procured in boxes very cheap ; but what you gain 

 in glass you partly lose from requiring so many sash-bars. 

 We should not care about having them much above 

 eighteen inches in length. All things considered, if we 

 were to roof a house most economically, we should obtain 

 strong machinery-cut sash-bars, dispense with rafters, 

 use glass from fifteen to eighteen inches wide, and say a 

 foot in depth, and secure means of ventilation without 

 touching the roof by the upright glass and wooden 

 ventilators at the ridge in the roof and in the back wall. 



Stages. These are generally shelves, arranged in stair- 

 like fashion, partaking less or more of the character of 

 the roof. For a general collection, the stage may be 

 from five to six feet from the glass roof ; for insuring 

 dwarf, compact, bushy plants, the distance should be 

 from three to four feet. The lowest shelf of the stage 

 should be a little higher than the shelf that surrounds 

 the house next the front glass. Where the roof is hipped, 

 even though the back wall be opaque, if the house faces 

 the south the stage should be hipped too, terminating in 

 a single shelf, broad or narrow in the centre. The north 

 part would be admirable for keeping many plants hi 

 winter, and exhibiting in summer those that were in full 

 bloom. In a wide house it is always preferable to have 

 several stages, in the shape of circles, ovals, or triangles, 

 whichever is most approved, with walks between them. 

 The expense, and the room apparently lost, are more 

 than compensated by the ease with which all the plants 

 may be examined, and the greater thickness with which 

 they may be safely set, as the pathway will be so many 

 breathing zones. (See FLOWER STAGES.) For low- 

 hipped, roofed, and ridge-and-furrow roofed houses, flat, 

 table-like, trelhsed stages will be the best ; the highest 

 plants being set hi the centre, or, if necessary, one being 

 placed now and then on a pot. As an improvement on 



this, where extreme economy was the object, we would 

 dispense with the wooden trellis, and substitute a bed 

 of earth, kept in its place by brick walls, the earth being 

 first covered with cinders, and then with pure sand, on 

 which to set the pots. The damping of this sand from 

 watering hi summer would be a source of health to the 

 plants, and save them from many visitations. Small 

 inclosures in such an earth-pit, if suitable compost were 

 used, would be excellent for the less hardy creepers, 

 which would be likely to maintain a lingering existence 

 if planted, as they sometimes are, hi a border close to 

 the front wall. 



Temperature. If merely preserving the plants is the 

 object, then artificial heat may only be applied to main- 

 tain a temperature of from 35 to 40. This low tempera- 

 ture must not, however, be long continued in a stagnant 

 atmosphere. It will, therefore, be necessary to raise the 

 temperature to admit air during the day. Where it is 

 desired slowly to grow the shoots, and to keep a winter 

 display of plants hi bloom, the temperature must not 

 sink below 45. In either case a rise of 10 or 15 

 may be allowed for sunshine hi winter. In summer, the 

 chief difficulty will be to keep the house cool by admitting 

 all the air possible, and having it on night and day. If 

 the plants are turned out hi to pits and shady places, 

 and even very sunny places if their nature requires it, 

 and their place is supplied with tender annuals, &c., 

 then more closeness and moisture must be obtained a 

 limitation of air and plenty of moisture giving all the 

 essentials of a plant stove. 



Artificial Heat. The best, because the most equal and 

 the cleanliest, is hot water ; and the simplest of all con- 

 trivances is the best : a compact little boiler, well set, 

 and a flow and return pipe on the simplest principles. A 

 small boiler and two or three-inch pipes are the most 

 suitable for a greenhouse where only quick and occasional 

 fires are wanted. Flues are far from being despicable 

 conveniences. In some respects, hi small houses where 

 a higher temperature is wanted at one end than another, 

 they answer better than hot water. When neatly built 

 they are no eyesore in a house. To insure draught the 

 flue should be at least a third deeper than it is wide, 

 and the mouth of the flue should be eighteen inches 

 above the bottom of the surface. For greenhouses, one 

 foot of four-inch pipe will be necessary for every forty 

 cubic feet of air, making allowance, less or more, according 

 to the surface of glass, or the presence of opaque walls ; 

 or, hi other words, taking the square foot of glass, it 

 would require a foot of four-inch pipe for every six feet 

 of glass ; or a foot of a common flue above the ground 

 for about ten or eleven feet of glass. 



Ventilation. Means should be secured for a thorough 

 circulation of air from the sashes hi front, and the highest 

 point hi the roof, as there the heat will generally be the 

 greatest. In cold weather in winter, unless there are 

 means for heating the air before it enters, the little given 

 should be at the top of the house, as thus the cold, dry 

 air would be heated and absorb the moisture before 

 reaching the bulk of the plants. When the air is very 

 dry, and the weather very cold, the less air that is given 

 the better. In such circumstances, the heating medium 

 should be cool before the sun strikes upon the house, 

 and then the sun-heat will raise the house the less ; and 

 10 or 20 for a short tune, from sun-heat, is a very 

 different affair from having that increase from artificial 

 means. For greenhouse plants, generally, in favourable 

 weather, too much air cannot be given, night or day, 

 from the middle of May to the middle of September. 

 For two months preceding May, and subsequent to 

 September, ah- should be given early hi the morning, 

 even if it should be withdrawn or reduced soon afterwards, 

 or early hi the afternoon. In whiter, unless the air is 

 very mild, it will be tune enough to give ah- by ten 

 o'clock, and shut up between two and three. When the 

 weather is very severe, one hour, or even less, hi the 

 middle of the day must be sufficient. In dull, close 

 weather, air should be given, though a brisk fire should 

 be put on during the day on purpose. When, however, 

 the greenhouse is changed into a vinery, a place for 

 growing tender annuals, &c., the forwarding of the 

 growth of Camellias, Epacris, Azaleas, &c., then the 

 temperature in spring and summer must be higher, and 

 the atmosphere closer and moister. By means of divi- 

 sions, you may have almost as many temperatures and 

 atmospheres hi one house as you please, by regulating 



