The Garden Under Glass

CHAPTER XXIII WATER FOR GREENHOUSE PLANTS When a Plant Needs Water It would be easy to answer that a plant needs water when it is dry, but it would be equally easy to find instances of a plant being very dry and yet not needing water. Bulbous plants, such as amaryllises, nerines, crinums, begonias, gesneras, calanthes (using the term bulbous in its widest meaning), are allowed to become quite dry, almost to the point of shrivelling, during their period of inactivity. A plant may be said to need water when in active growth, but to need the artificial application of water o nly at a time when the resources of moisture in the soil have been ex-hausted, and the plant, lacking the necessary moisture, is unable to perform its proper functions. Of course, the canons of good culture forbid us to allow a plant to reach this extreme state, just as the canons of good sense and the demands of good appetite will not allow us to be faint with hunger before replenishing our internal larder. In the outside garden there is little difficulty in knowing when the plants should be watered, and little danger of giving them too much, but greater care and more exact knowledge is needed in dealing with plants in pots, pans, tubs and boxes. There are, however, several well-proved means of ascer-taining the need of a plant. It is a very unsafe plan to judge of the requirements of a plant by the appearance of the surface soil of the pot. This may appear quite dry 229