Watering your yard is a substitute for rain. We must do it when necessary, with due regard for the needs of the plants and for the use of water. Rainwater is best for plants because it is not chlorinated, but water from the public supply is definitely sufficient.
Watering Your Yard: When and How Often
Watering isn’t required daily. In cool conditions when there has been raining it is not needed at all. Remember that it is possible to over-water, which is unhealthy for plants. However, in hot or dry conditions more frequent watering should be done. Many experienced gardeners say that it is best to give your plants a good soaking once a week.
Gardening expert, Joy Larkcom, explains that in dry conditions water is quickly absorbed by the surface soil, so if you lightly water the water will not get down to lower layers. It is, therefore, better to give a thorough soaking every few days, so that lower soil layers may be moistened . The Royal Horticultural Society (RHS) explains that light watering encourages shallow rooting, which is not ideal .
Containers and raised beds dry out quicker than the ground does. You do not need to water them daily, but you should ensure that the soil in pots and raised beds is never allowed to become dry. Test with your finger to see if the top two inches have gone dry, and if so water the plants.
In hot weather, lawns need watering three times a week. A sprinkler will give an all-over dose of water, but it is wasteful, and in certain parts of the world there may be sprinkler bans. A hosepipe will work, but it should have a spray attachment at the end. The rose (the head of the spray) should be fine so that it distributes a mist of water over the lawn.
However, many gardeners worry unnecessarily when they see grass going brown in dry weather. They fail to realize that the roots are still alive and that with watering or rain new shoots will spring up. Many people do not know that grass is unusual in that unlike other plants, which grow from the top of the shoot, grass grows from just above the root, so dead grass above root level is not fatal to the plant.
Most soils have some sand in them, but soils with a high sand content drain very quickly, so need more frequent watering than others. If your soil is sandy be aware of this problem and keep an eye on it to prevent drying out.
Time of Day to Water
The RHS says that watering should be in the early morning (between 8.00 and 10.00) or in the evening.  This is especially important in bright conditions, as in strong sunlight water droplets on leaves act as magnifying glasses focusing heat which can scorch leaves. Doing watering in the morning is the better of the two options, as it is during the daytime that plants use up the most water,
How to Water
Joy Larkcom says that the golden rule is to water gently and thoroughly.  The hose or watering can should have a rose at the end. This is an attachment with the holes in it. The rose that you use is determined by what plants you have. Trees and shrubs do not need a rose at all, though having one does no harm. Larger plants, such as roses, do not need a fine rose, but seedlings should only be watered with one, as this sprays more lightly and thus avoids damaging the delicate plants.
But if possible do not spray directly onto the plant, it is far better to direct your water jet onto the soil around the plant, thus directing water towards the roots, where it will be absorbed. You can do this more easily with shrubs and trees than you can with flowers.
- Grow Your Own Vegetables, Joy Larkcom, Frances Lincoln Limited, 2002, pp 77-80. While this book specialises in vegetables, what it says is applicable to flowers, lawns and shrubs.
- The Royal Horticultural Society Encyclopaedia of Plants and Gardening Editor in Chief Christopher Brickell, p614
- Ibid, p614
- Larkcom, p78