CULTIVATION OF VINES IN GREENHOUSES. 289 



grapes. The water should have been warmed by exposure to 

 the air. 



Temperature of the house. 



If the house were covered with waterproof canvas at night 

 during frosty weather, very little fire heat would be requisite, 

 and vines and all plants kept in the greenhouse much benefited. 

 In winter the thermometer should never exceed 40° when the 

 assistance of artificial heat is required. About the beginning of 

 March, when the buds of the vines are well swelled, the heat 

 should be raised to 50^ if dull weather, and 60^ or 65° during 

 the day if clear weather. This temperature will be advan- 

 tageous to geraniums, fuchsias, &c., at this season. When the 

 mornings are frosty in this month the thermometer in the green- 

 house is generally down to 45° or 46° with me. I have had it 

 as low as this even when the grapes were in flower, and I have 

 never observed that they sustained any injury by this low tem- 

 perature. As the season advances, of course the heat ought to 

 be increased to 55° or 60° at night, and to 70°, 75°, or 80"" 

 during the day. 50° and 55° at night may be safely taken as a 

 general rule for the first and second month's growth. Air will 

 be required both night and day at all times when fire heat is 

 necessary. In mild weather, in winter, I give plenty of air 

 during the day, and a small portion at night also. 



No front air will be required in the early part of the season 

 unless the weather is very mild. In summer, when the nights are 

 warm, a small portion of air should be left on all night at two 

 lights. If the temperature be low in the morning, shut the house 

 and give no air till eight o'clock. It might be sooner or later 

 according to the situation of the house. It is impossible to lay 

 down rules as to the time when air ought to be given, or the quan- 

 tity requisite at all times, nor is it necessary, for this department 

 of the business is sure to be best performed by the person who 

 keeps general principles constantly in view, and not by him who 

 is entirely guided by written directions. It should always be 

 remembered that heat should accompany light, and coolness 

 darkness. 



Pruning. 



I formerly recommended the long system of pruning vines as 

 best adapted to late vineries ; but as the vines must be confined 

 to the rafters in a greenhouse, in this case I Avould advise the 

 adoption of the spur system. A chief objection to this mode of 

 pruning is, that in the course of time the spurs get long and 

 ragged ; but if the border is in tolerably good condition and 

 covered as I have directed, tlie vines will push vigorously from 

 various parts of the old wood of the spur, which may therefore 



