Watering must be attended to, especially during dry spells. One good soaking a week is much more valuable to plants than many light sprinklings which do not wet the soil to any appreciable depth. On sandy and very light soils it will be necessary to water thoroughly every day or every second day during the dryest part of the season. Where it is not possible to water all the plants thoroughly at one time, divide the beds into sections and water the various sections in rotation. Watering in the later afternoon or evening hours has a more lasting effect than during the hotter portion of the day. Watering can be overdone as it can be carried to the point where the soil becomes water-logged and will consequently sour. Too much superficial watering of open-ground plants induces surface rooting which is not satisfactory, as such plants do not have access to large stores of food, and consequently cannot withstand drought successfully. Transplanted perennials should be watered thoroughly and left alone a few days till they become somewhat established.
The statement is sometimes made that water from wells is too cold to be suited for watering plants, and also that such water often lacks chemicals which serve as plant food. On the contrary, successful gardeners often water plants at midday on hot summer days in order to gain the cooling effect of the water when it is most needed. It is also believed by some experienced observers that water falling on the soil reaches the soil temperature very quickly after being absorbed and in all but a negligible number of instances, before it reaches the roots of plants. With regard to the question of the amount of plant food contained in water from a deep-driven well as compared to the amount found in surface water such as that flowing in a creek or river there seems to be little reason to think that water from wells is lacking in plant food to such an extent as to make it less valuable than surface water. It is now agreed that surface water contains more solid matter in suspension while subterranean water has its load of solid matter in solution. Therefore the plant food which occurs in water from a driven well differs from the plant food found in river water merely in being more likely to occur in solution rather than in suspension. The water which is taken from artesian wells is not always sterile and often contains nitrates in large quantities due to the reduction of the nitrates which occur in deep layers in the soil. When this water is used for irrigating the surface layer 6f the soil, the nitrifying bacteria change the nitrites back to nitrates. In regions rich in humus, ground water often contains organic as well as inorganic matter. Well water may and often does contain plant food which is very valuable in the form of nitrates or ammonia.