1 88 Commercial Gardening 



winter months, in this country. Top ventilators should be provided, but 

 their use for the admission of fresh air or the reduction of temperature 

 must be severely limited. Bottom ventilators on both sides of the houses 

 are a necessity, and there should be a number of them placed so that the 

 outside air passing through them into the houses will be warmed by the 

 hot-water pipes ere it reaches the plants. Top ventilation coupled with 

 bottom ventilation tends to dry out the atmosphere quickly, and a dry 

 atmosphere is not conducive to the best results. Moisture - holding 

 material, such as clean cinders or gravel, on the stages is essential, and 

 if the plants can be raised above this material on a light open trellis 

 staging so much the better. 



Practically all Orchids need far less moisture, both at the roots and 

 in the atmosphere, during the period that follows immediately upon the 

 completion of their growth for the season. In the case of Cattleyas, and 

 especially Dendrobiums, the season of "rest" is very marked, and an 

 abundance of water while the plants are comparatively inactive will quite 

 spoil flower production and at the same time enfeeble the plants. Cypri- 

 pediums, Pbalsenopsis, Oncidiums, Odontoglossums, and Coelogynes do not 

 require so decided a season of rest, and with a few rare exceptions, that 

 do not concern us here, they must not be "dried off", to use a technical 

 phrase that is well understood among Orchid cultivators. 



A word or two as to the potting material. There was a time when 

 peat was the basis of all potting composts for Orchids, but it is wellnigh 

 impossible now to obtain the best fibrous peat, such as formerly delighted 

 the hearts of growers. Good substitutes for peat are found in Polypodium 

 fibre, or the increasingly popular Osmunda fibre. These fibres are imported 

 in large quantities, and, in combination with the large-headed sphagnum, 

 form the great standby among orchidists. A small addition of oak or 

 beech leaves, gathered clean at the time of fall, and stored under cover 

 for a year, is made by many growers, and where the watering i done 

 with great care this addition encourages root action and increases the 

 vigour of the growths. An excess of leaves, however, tends to the pro- 

 duction of large but not substantial flowers; therefore this must be 

 guarded against, because anything that detracts from the lasting pro- 

 perties of the blooms reduces their value in the market. 



Pure air and good light are of the utmost importance in Orchid culture, 

 and we have only to observe how splendidly Orchids grow in districts 

 far removed from towns and factory districts, and then inspect collections 

 in the immediate neighbourhood of a great town or city, to discover how 

 environment influences the plants. Further, the work of sponging the 

 plants and cleaning the roof glass in districts where the atmosphere is 

 laden with impurities is very considerable, and would materially increase 

 the cost of production without any compensating advantage. Orchid 

 flowers for the great cut-flower markets are produced chiefly in such 

 pleasant places as Haywards Heath and Balcombe, Broxbourne, St. Albans, 

 Cheltenham, the outlying suburbs of Liverpool and Manchester, &c. 



