ON GREENHOUSE PLANTS. 699 



and the air passes up amongst the foliage of the plants laden 

 with moisture. This is especially the case when they are damped 

 two or three times a day. 



In the centre of the house it is usual to have shelves placed 

 in tiers one above the other. These should also be made of slate 

 and covered with gravel stones ; but it is a better plan to have 

 a flat bed raised 6in. above the ground. In the centre of this 

 tall plants in tubs or large pots may be placed ; or they may 

 even be planted out, and then others not quite so tall arranged 

 next them, the plants getting lower towards the edge. This bed 

 should also be covered with loose gravel. The paths should 

 either be tiled or cemented over, and .it should be noted that 

 cleanliness is a very important consideration. 



The temperature of this house should range from 5odeg. to 

 6odeg., and in all cases it should be at least .sdeg. lower in 

 the night than in the day, both in this and the growing- 

 houses. 



When the soil is very heavy and wet, the ground on which 

 the greenhouse is to stand should be raised above the rest, so 

 as to ensure ' perfect drainage. The growing-pits will also, in 

 such cases, be better raised instead of sunk. 



The Growinc-Houses. — Of these there should be at least 

 two : one structure can be divided into two parts, and sometimes 

 three divisions can .be made. The sunk house or pit is the best 

 form, as, not being so exposed, the heat is more easily retained. 

 This is a house having a low exterior wall about ift. high on 

 which the roof rests, coming down nearly to the level of the 

 ground. It is entered by an exterior flight of steps, the path in 

 the centre being 3^ft. below the level of the ground; side shelves 

 are fitted similar to those in the greenhouse, but they may be 

 wider. The two divisions should be warm and cool respectively, 

 the first having a winter temperature ranging from S5deg. to 

 65deg., and the second from 45deg. to 5sdeg. In summer 

 artificial heat will not be necessary in the cool end, and in the 

 warm one only during very damp weather, or for the purposes of 

 propagation, when a little bottom-heat may be required. The 

 warm pit can be used for growing plants on, and for bringing 

 them into blossom quickly, or for gentle forcing in the spring. 

 The cool pit will serve for hardening off plants in blossom before 

 shifting to the greenhouse, as well as young ones that are 

 intended to grow outside in the summer ; it can also be used 

 as a resting pit. Both the pits can be used for propagation, 

 but for this purpose they should be fitted with proper cases 

 (see Chapter " On Plant Propagation "). 



It is a good plan in the case of these houses to make sections 

 of the roof to lift on hinges, so that when the weather is suitable 

 they can easiiy be propped open and the plants shifted without 

 passing up and down through the doors. 



