Garden watering systems

Consider automatic versus manual watering

Automatic irrigation systems can water gardens efficiently. But they can also distribute far more water than your garden needs if they aren't well designed, programmed and maintained.

When you water a garden by hand, the risk of over-watering is very low. You quickly notice when the soil stops absorbing water and it starts to flow sideways. You can easily identify the plants that look more stressed than others and you'll naturally change your watering habits when the seasons change.

Automatic irrigation systems aren't a set-and-forget option. They need careful consideration before you install and operate them. We recommend you get an irrigation professional to help design your irrigation system.

Find good irrigation design advice

So, you've decided an irrigation system is probably right for you. The best possible thing you can do now is get the best advice. Unfortunately, this level of training and skill isn't easily found in your local hardware store or nursery.

In Sydney, only dedicated irrigation system retailers tend to employ professionals that are trained and certified by the Irrigation Association of Australia. Visiting these businesses is the cheapest way to access expert advice. This expertise can be relatively expensive, but most irrigation suppliers will provide plenty of free advice in the shop – especially if you come prepared. With a little help, you'll find all you need to install your own high quality solution that follows the supplier's professional design advice.

Start with a plan

Your garden's design and your water supply are the main factors that determine your irrigation system's design. So, if you've decided to visit a specialist irrigation shop for help, take a simple plan of your garden's design. Professional irrigators always start by drawing a plan of the garden to scale. A scale of 1:100 works well for most gardens. The idea is to ensure each area is identified and assessed for its water needs.

You need to consider lawn areas separately to garden beds. Special areas like groups of trees and vegetable gardens will also have unique water needs. Consider each of these areas as a separate irrigation zone. Your professionally designed irrigation system should allow each zone to be watered individually.

Know your rate

No matter how your system is controlled, you'll need to know how much water can be supplied each time your garden is watered. You can check this simply with a bucket and stop watch. Measure the number of litres you can get in your bucket per minute. This result will be used in your irrigation system design to calculate the maximum number of sprays, nozzles or drippers you can install in each irrigation zone.

To complete this exercise, you need to understand the flow rates of irrigation fittings. Sprays will emit the most water while drippers will emit the least. Without knowing these flow rates, you can easily expect too much from your water supply and your plants will suffer. A specialist irrigation retailer will help you find commercial grade irrigation fittings with specific flow rates for your needs.

Choose the right irrigation controller

You need to water each irrigation zone in your garden independently. This enables you to choose how often and how long you're going to water in each zone.

At the core of an irrigation system is the controller. Basically, a controller uses a timer to control valves that allow water to flow to a specific irrigation zone, at a set time for a duration that's manually set.

At a minimum, look for an irrigation controller that senses when it has rained. Otherwise, your clock based controller will eventually find itself watering in the rain.

The duration of each watering event is determined by:

• the soil's capacity to hold water
• the irrigation rate. 

Once you know this, it won't change until you improve the soil.

The frequency of watering is determined by your plants and the local climate conditions. This should change in response to changes in climate. For example, you can expect to water far less frequently in winter and more often in summer. Make sure your irrigation controller has a seasonal control feature.