Most succulent plants, when in full growth, take as much water as any pot plant, but since they are constructed to exist with little, it is better to under-water than to kill theby over- .
At the beginning of the growing period water is given occasionally, and gradually increased as required. As with ordinary plants, watering is only necessary when the soil begins to dry out after the previous application. The soil on the surface may look dry, but to make sure it is best to scrape down a little way or, when experience is gained, to judge by tapping or lifting the pot.
With almost alland most of the other succulents whose growing period coincides with our summer, three or more waterings a week may be needed in hot weather. Obviously, plants in small , and those with vigorous systems, will need a lot of water.
Towards the end of the growing period — about mid-September for the average succulent – watering is gradually curtailed; this helps ripening.may shrivel a little at this time, but this is quite natural. In the resting period one light watering a week is ample, and if the conditions are on the cold side, much less may suffice. In winter only enough water should be given to prevent the soil from drying out completely. At this time especially, if in doubt do not water: the roots are largely inactive. Never splash water about: this may lead to condensation on the plants if the temperature falls.
Where succulents have well defined rest periods these must be carefully observed. Not until the first signs of new growth are clearly visible should watering begin; and as soon as the plant begins to shrivel watering should be sharply restricted, and with many plants, as specified in the alphabetical list of genera, entirely stopped. Otherwise rotting often follows, or at least flowering may be prevented. Seedlings may, however, usually be watered sparingly in their first resting period. With these plants it is always best to be cautious about quantities. The method of watering grit in which pots are buried is ideal.
It is wise to avoid pouring water on to plants; it may possibly cause rotting and I have seen drops of water acting as lenses in hot sun and causing scorch marks. Some growers in warm climates syringe their plants lightly in the early evening to simulate the desert dew. This may be carried out in very hot weather, but it is rarely necessary in cooler climates and can easily be overdone. An occasional spray, with water to which a little soft soap has been added, is useful to clean the plants, especially in the sooty, acid-laden air of towns or in dusty rooms. On such occasions the plant should be sprayed again with clear water, and then shaken to avoid water lodging in any crevice. Woolly cacti may be ‘shampooed’ with a soft brush dipped in soapy water, and succulents with stiff, such as agaves and aloes, may be gently washed with a soft rag dipped in soapy water and then cleaned off with clear water; but avoid this with plants having a ‘bloom’ on the leaves.