284 GARDENING FOR BEGINNERS 



noted for their oil stoves of all kinds, have brought out some good forms 

 for heating greenhouses. Though varying in power the principle remains 

 the same ; it is that of an upright boiler, connected by means of hot- 

 water pipes with a standard of the same height as the boiler. This 

 allows a free circulation of water, and of course the heat given off is 

 considerable. The heating apparatus consists of a large sliding tank for 

 the oil and one or more burners. A sufficient quantity of oil is stored 

 to bum from sixteen to twenty hours, thus avoiding soiled hands and 

 unpleasant work late in the evening. Of course the lamp requires regular 

 and careful trimming, a remark that applies with equal force to an ordi- 

 nary table-lamp. Even a table-lamp of the duplex kind will protect the 

 plants in a small house from danger during a sharp frost. The different 

 forms of hot-water apparatus heated by oil are perfectly free from smoke 

 and smell, provided always that the lamp is thoroughly trimmed. It is 

 portable, therefore can be readily shifted to that part of the structure 

 requiring the greatest amount of heat. As the lamps require no chimneys, 

 flues, or fixtures of any kind, and the dirt and inconvenience of stoking 

 are entirely obviated, the different forms of oil stoves may be recom- 

 mended to the amateur. A little experience will determine the best 

 position for the stove, which should not be closer to the plants than can 

 be helped, consistent with being in the best position for heating the 

 greenhouse. 



As with proper attention the lamps are quite clean and free from 

 smell, these oil stoves can be used where the greenhouse or conservatory 

 is attached to the house, with a communication between the two. They 

 are not in the least unsightly ; indeed, some of the better forms are 

 quite ornamental. There are also several forms of boilers heated by gas, 

 these being very convenient and effectual, provided the gas cannot have 

 access to the structure. When heating a greenhouse too high a tem- 

 perature must not be maintained during winter. The object is simply 

 to keep the plants free from frost and not to unduly excite them, for those 

 that experience a period of comparative rest during the winter grow with 

 greater freedom than those which have been placed under warmer con- 

 ditions at the dull period of the year. For an average greenhouse, with 

 the usual occupants of such a structure, a night temperature of 45 degrees 

 is quite sufficient ; indeed, it may during very severe weather drop 

 another 5 degrees without injury. As previously stated, however, if 

 a display of flowers is needed, a night temperature of 50 degrees must be 

 ensured. Even in the depth of winter artificial heat may be frequently 

 dispensed with for days together ; but after a spell of wet, dull weather, 

 even when no frost is likely to occur, it is sometimes advisable to light 

 the stove for a short time to dry up superfluous moisture. 



Many forms of propagating cases for seeds and cuttings are heated 

 with an oil lamp ; but an objection to these is that they give off too 

 much heat, hence the young plants quickly become debilitated, and are 

 not so strong as those raised in the ordinary atmosphere of the green- 

 house. 



Potting Soils. The preparation of soils for potting is important, 



