The Garden Under Glass

VENTILATING AND SHADING 265 house are uplifted for the whole length of the house, and where the lights also at the front open outwards by means of hinges affixed at the top. It is not a wise plan to have only every alternate light to open. Better by far have them open the whole length, so that the house can be fully aired. The remark applies likewise to the lower ventilators. In a span-roofed structure the top lights on both spåns and the bottom lights at the sides should be made to open, or the ventilation would have sometimes to be put on the windward side. In a plant house provision should also be made for the air to be admitted at a point (in the wall) where it will be forced to pass over the hot-water pipes before reaching the plants ; but this does not do away with the necessity of the lower lights being made to open, for they will be required when a füll flood of air is needed. Whether the lights be manipulated by means of a screw or a lever matters little, though personally I prefer a lever which, with the aid of a bolt screwing against the bar, can be held in any position. The screw system is strong, but somewhat longer to work and requires frequent greasing. Hardening Off Readers have been often advised to harden off plants, and it is presumed that they understand the meaning. But while realising its meaning they may not exactly know how to set to work. Many of the subjects which are to be hardened off for eventual planting in the outdoor garden are not in the natural way likely to be killed by frost, others can under ordinary conditions stand several degrees of frost without injury, while others again, though un-injured by cold, yet are too tender to live during frost.