DENDROBIDM. 11 



have made their season's growth, to the cooler and drier part where they 

 can have a period of rest, which can be promoted by withholding water, 

 or what would he better still, into an early vinery, if snch accommo- 

 dation is at hand. The chief requirements of a Dendrobium house are, 

 that it should be sufficiently lofty to allow room for the development 

 of the stems of those species which have them long, and to admit of 

 an easy circulation of a large body of air within, by means of ample 

 ventilation; that the heating apparatus should be powerful enough to 

 maintain the required temperature in all seasons ; that the middle stage 

 — if the house is span-roofed — should be raised high enough to bring 

 the plants placed upon it as near the light as possible ; that it should 

 be provided with a tank beneath the stage sufficiently capacious to hold 

 as much rain-water as may be required for the service of the house ; 

 and with strong iron rods affixed to the rafters, from which baskets, 

 rafts, blocks, pans, etc., may be suspended. 



Temperatures. — In consequence of the drying and thence exhausting 

 effects in plant houses of the heat given out by radiation from 

 iron pipes filled with hot-water, it should always be the aim of the 

 cultivator to maintain no higher temperature by that means than is 

 absolutely necessary to secure the well-being of the plants. The range 

 of temperature to be maintained by hot-water pipes that is best suited 

 for any particular class of plants can only be ascertained by experiment 

 and observation; hence, for Dendrobiums it has been found that in the 

 climate of London, from November to February the night temperature 

 of the house in which they are cultivated should not descend below 

 13° C. (55° F.), with a rise of about 3 D C. (5° F.) during the day. 

 During March and April, when most Dendrobes start into growth, the 

 night temperature may range from 15° — 18° C. (60°- — 65° F.), with a 

 rise of 3° — 5° C. (5° — 9° F.) by day, by fire-heat alone ; but with 

 sun-heat it may rise from 6° — 9° C. (11° — 16° F.) above the night tem- 

 perature. During the summer months, that is, from May to August, 

 when growth is most active, the night temperature may be raised to 

 18° C. (65° F.), with a rise of 3°— 5° C. (5°— 9° F.) by day, by 

 fire-heat, or even 6° — 9° C. (11° — 16° F.) by sun-heat. During 

 September and October, when the plants will be finishing their season's 

 growth, the temperatures may be reduced to those of March or April. 

 Excessive temperatures can always be reduced by careful ventilation. 



Watering. — The frequency and amount of watering must depend on 

 the season of the year and the condition of the plants, whether they 

 are in active growth or at rest. General directions may be given as 

 a guide, but much must be left to the judgment of the cultivator. 

 Thus, in the winter months, when the plants are at rest, water should 

 be given only often enough to keep the compost and surface moist, 

 and prevent the latest formed stems from shrivelling, the amount 

 being gradually increased as the young shoots appear ; but when the 



