Irrigation is all about maintenance, moisture maintenance to be specific. Even though in winter, water shortages are far from our minds, it is timely to start thinking about irrigation. When I first started landscaping, I was under the impression that if you irrigated a dry garden it would soon become a wet one. Though this may be true if you deep-water with a hose for long periods, it is not the case if you install an irrigation system. A garden irrigation system, with a timer, little black pipe and myriad nozzles is actually a water maintenance system. This means it is effective at maintaining moisture in the ground after a good dose of rain, if you use it in conjunction with mulch and a timer. This is quite different from the idea of waiting until the garden is dry then giving it some water. In wet weather, water is stored in the soil and if we protect the surface with a thick mulch layer we can keep the soil moist long after the sun has come out. If we irrigate as well, it's possible to keep the soil moist for months at a time.
As a rule, when it comes to irrigation I like to go for drippers rather than sprayers. Drippers provide tiny droplets of water close to the base of the plant which means much less water is lost into the air through evaporation.
In vegetable gardens I've reverted to sprinklers because of their versatility and moveability. A vege garden is, after all, a moveable feast. A timer, in my opinion, is also a prerequisite simply because despite our best intentions we all, from time to time, forget to do things and one of the first things to drop off the must-remember list is watering the garden.
Once your system is up and running, it's pretty much hassle-free - though not absolutely maintenance-free. One of the most common problems with irrigation is the nozzles that deliver the water to the plants get filled up with grit and stop working. A filter at the tap can help eliminate this but not completely, so it pays to check everything once a month or so and change blocked nozzles if required.
Another handy thing to have on hand is stoppers. These are little buttons you place in the irrigation pipe should you want to move a nozzle: as your plants grow moving the irrigation from time to time will become necessary. Also, knowing your water pressure predetermines how your system will be set up. If you have a large garden you may need to split your irrigation system in to two or even three lines because there is only enough water pressure to water one line at a time. Certainly if you wish to irrigate your lawn, this will definitely be the case.
Firstly, test your water pressure. To do this, turn your tap on full, then place a 10-litre bucket under the tap and time how long it takes to fill right to the top. This will give you a basic idea. If you are running your irrigation uphill, take a hose to the top of the hill and measure the pressure from there.
Turn off the mains water supply then remove the tap head from the pipe. Install a "T" section for the irrigation to sit on, then reinstate the tap head. This will allow you to use the tap without removing the irrigation every time.
Count roughly how many plants you wish to irrigate and how you wish to irrigate them. Remember, more water nozzles release more water, which reduces overall water pressure, so plan carefully.
Attach a timer to your tap. If you are installing a split system, make sure your timer has room for two lines.
Run the pipe around the garden. Avoid making joins unless it is necessary as this reduces water pressure.
Attach the nozzles, making sure every plant is receiving water. Use nozzles with restricted angles to avoid wasting water on paths or driveways.