Water is becoming an increasingly scarce and costly resource. Hence a well planned garden with appropriately selected plants and an efficient watering system can play a major part in determining the size of the water bill. Designing and operating an effective watering system will be made easier by paying attention to the following when planning your garden.
1. Consider your climate and aspect when selecting plants. Try to choose those which are adaptable to your conditions. Plants chosen from different climatic regimes usually require much more attention and often lots of water to produce the desired effect (for example trying to grow rainforest ferns in a dry area).
2. Soils vary greatly from site to site and careful consideration needs to be given to a plant's soil requirements. Putting it in an abnormal environment can reduce its efficiency to use water and hence the need for excessive application to make it grow. Soils can be modified to suit particular plants, as well as have amendments added to improve drainage, water holding capacity and water penetration.
3. The type and position of lawn areas contributes significantly to the overall water consumption in a garden. Select lawn species wisely and don't be afraid to let them dry out a little over the dry season - lawn species have a remarkable ability to recover when the rains come.
4. Mulching is one of the best ways to minimise water use.
5. Keeping plants healthy (well fed and free from pests and diseases) allows them to make better use of the water applied - therefore you will need less. Also do not leave too much exposed soil between plants. If the plants are reasonably close their foliage will shade the ground and minimise water evaporation.
6. Getting professional advice to assist in planning your garden and watering system can be an investment in future cost savings. Good advice is often available from suppliers and installers of irrigation equipment so take advantage of it.
SPRINKLER SYSTEMS
The old fashioned method of watering gardens by sprinklers throwing water about fairly vigorously is out of favour in most smaller gardens. It is still popular in larger gardens and parks, but even there a lot of time is spent dragging hoses into position. There are two basic methods of watering more efficiently. The more solid installed irrigation systems involving high pressure, high discharge watering, as is the case with pop-up systems, are very useful over larger areas and with lawn. These are carefully organised, using different nozzles to throw out different water patterns, so that all areas are covered with minimal amount of water being wasted on paths, or over watering.
The second efficient method of watering is micro-irrigation. This can be via trickle irrigation or by using micro sprays. These methods can ensure water is delivered to only where it is needed. It needs only low pressure and discharge is slow so that water is able to soak (infiltrate) into the soil therefore avoiding puddling or runoff.
Kits and individual pieces are available from most nurseries and hardware stores, so that home gardeners and professionals can design and construct their own irrigation systems. They are generally easy to construct as good instructions and guides are provided at sale points.
Several points should be remembered when selecting which equipment to use.
Drippers are more suited:-
To watering individual plants such as potted plants and isolated trees and shrubs.
They are excellent for heavy clay soils where water penetration is slow.
The concentrated wetting pattern they provide means they are better on severe slopes(located up the slope from the plant).
They are preferable for plants which may suffer from fungus diseases, such as powdery mildew, when they are watered from above.
They will still work when water pressure is extremely low.
They help keep weeds down as less surface area of soil is damp enough for seed germination.
Micro sprays can either be spray jets discharging a course to fine spray or sprays which discharge the water in streams or fingers. Both are suited to:-
Fitting into any garden shape with a variety of watering patterns and flow rates available.
Free draining soils where water infiltration rates are fairly high. They are also generally better for shallow rooted ornamentals, shrubs and annuals.
Other types available are Misters to increase humidity and Rotor sprays for larger areas.
Once all this information is taken in to consideration you should be able to tell what is needed where and how much equipment you will need to buy. Remember that you will have to install different lines if you want to use both drippers and sprays, as they work on different pressures, though they can be connected to the same tap using two shut off valves and a tee piece.
High Discharge Irrigation
Irrigation for large areas and lawn requires a high discharge rate, requiring a high water pressure. Installing these systems can be rather complicated as it necessary to work out total discharge of all sprinklers required and choose suitable width pipes to provide the necessary pressure. As it is important that all sprinklers receive the same pressure, solenoid or gate valves may need to be incorporated to balance the system. These difficulties are most relevant when considering very large areas. A pop-up system in a domestic lawn will often be comparatively easy to install as long there are not too many sprinklers required.
Other Watering Systems
Most other watering systems require more manual labour, mostly the moving round of hoses to appropriate places. Water is discharged using a wide variety of sprinklers which can vary in the area they cover and the droplet size produced. Sprinklers that rotate are better on heavier soils as they allow water to penetrate and reduce run-off, or slow applications, as with soaker hoses are also good. Free draining soils such as sandy soils will cope better with continuous heavy applications. Watering cans still have their place, as they are ideal for giving a set amount of water to an individual plant.
Automatic Systems
There are now available a wide range of automotive systems which work either by using clockwork or computers. Ranging in function and price you can obtain systems which simply allow the water to flow for a certain amount of time once you have turned it on, to systems which work independently by utilising equipment which measures moisture in the soil or air.
WHEN TO WATER
To minimise water wastage, watering at the most suitable time and in the proper manner is a must. Firstly you should consider how much watering needs to be done according to the types of plants and soil present. If you have a garden with plants that prefer arid conditions frequent watering will not be as necessary as it is for a rainforest garden. Observe your plants and see how long they last before they start showing signs that watering is necessary. Plants suffering lack of water may show signs such leaf wilt, leaf yellowing, leaf burning and stunted growth, though it is not recommended to wait for such symptoms to occur. Over watering can result in soft, lush, leggy growth with few flowers or fruit and a susceptibility to disease. Too much watering will leach nutrients from the soil.
Also observe your soil, a free draining sandy soil with delicate ornamentals may need watering up to twice a day in dry weather, while a heavier clay soil which holds a lot of water may require watering once every three days. Do not water on a strictly regular basis, make sure it is needed.
The time and manner of watering should also be considered. It is generally much better to more thoroughly, less frequently, as this will encourage deeper roots and make the plant less susceptible to dry periods, though there are plants which are naturally shallow rooted and require more frequent watering. Do not water during the heat of the day, as much of the moisture will be evaporated into the air and top layer of warm soil. It is much better to water in the evening or early morning. If you have an automated system with a timer, watering in the middle of the night is a good idea, particularly with large irrigation systems, as the water pressure is usually better then. Evening and night watering though can produce mildew problems as the leaves stay wet for a long period. When timing your watering according to the weather, it must be kept in mind that a windy day can be more drying than a windless, hot day, and that long periods of cloud cover do not mean that the soil is not drying out - plants still drink up water whether the sun is shining or not.
Want to Learn More?
Study our Irrigation Gardens Course
Ten Lessons, 100 hours
Experiential, practical, correspondence course.
Start anytime, study from home, anywhere in the world
Ten lessons as follows:
Introduction to Irrigation
Soil Characteristics & Problems
Estimating Plant Needs & Irrigation Scheduling
Drainage
Types of Irrigation Systems
Trickle Systems
Design Specifications
Pumps & Filters
Selecting the Right System for a Plant
Design & Operation of Systems.