Watering Zones

Introduction

The Watering Zones concept recognises that different plants have different needs - their habits and water requirements vary enormously. Some need to be watered frequently, others only rarely.

For instance, a Western Australian plant which has evolved in our climate over thousands of years, will need little, if any, water to survive our hot dry summers. On the other hand, a rose will need to be watered more frequently over summer - and some bedding plants and most vegetables still more often. There's no point in putting them all together in the same area of your garden.

But by grouping plants together on the basis on their water needs -to make Watering Zones - the gardener will know that each plant in the zone is getting as much water as it needs, and that no plant is being overwatered.

The result is good healthy growth - and a reduced water bill!

Please Note: There are water efficiency measures in place for Western Australia. If your plants need to be watered more frequently than the watering roster for your area allows, additional watering will need to be done with a hand held hose.

All Plants are Not Equal

Garden plants are divided into three groups according to their need for water.

• Watering Zone 1 - plants with a low water requirement. They will only need occasional watering over summer. Perhaps once every two weeks or longer.
• Watering Zone 2 - plants with a moderate water requirement. These plants will need to be watered every 3 to 7 days.
• Watering Zone 3 - plants with a high water requirement. These plants will need to be watered every 1 to 2 days.

A comprehensive listing of common plants and their rating is given elsewhere on this site (Common Plants and their Watering Zones), under 'Plant Listing'.

Selecting the Right Equipment

In general, an automatic or semi-automatic watering system is easiest to use, and most efficient.

Lawns (Zone 2) are best watered using sprinklers - preferably a type producing course drops, to reduce evaporation. Don't mix sprinkler types - or brands - on the one watering line.

Gardens use the least water when serviced by drippers and tricklers which irrigate individual plants.

• Densely planted flower beds may be watered by microsprays.
• Don't mix drippers/tricklers with sprays/sprinklers on the same line.
• All garden beds should be heavily mulched to minimise evaporation.

How to Water the Different Watering Zones

Once your garden is designed and planted into three Watering Zones, it is important to apply water correctly in order to gain the greatest savings.

• Each zone must be capable of being watered independently from the other zones. For installed systems, this means separate lines controlled either manually or automatically.
• Each plant whether in Zone 1, 2 or 3 gets the same amount of water each time the system is turned on (a Standard Drink). What varies is how often each zone is watered.
• Your watering schedule should vary with the seasons. The "Guidelines for Watering Zones" table is a good indication of watering frequency at different times of the year.

Know how much water you are applying

• A "Standard Drink" refers to the amount of water you should give your lawn or garden in any one watering. In the metropolitan area the Standard Drink is 10mm depth of water, or 10 litres/m2 of watered soil. Water Corporation Regional Offices have information on Standard Drinks for country towns.
• Catch Cups can be used to calibrate a system where garden water is applied through sprinklers or sprays. They are available from Nursery Industry Association and Irrigation Australia members, and contain full instructions.

Guidelines for Watering Zones

Based upon a standard drink of 10 litres/m², for established plants in improved sandy soils in Perth.  Remember that water efficiency measures are in place, so you may only water on your rostered days. Additional watering will need to be done with a hand held hose.