Know your soil type
Soil types across Western Australia vary greatly. Clay soils feel sticky, hold moisture for long periods but can become compacted and absorb water slowly. Sandy soils feel gritty, are thirsty and will take in a lot of water, but they dry out quickly. Loam is the ideal soil type with roughly equal portions of sand, silt and clay. In general, Perth’s coastal soils are sandy, and benefit greatly from soil amendments (such as clay) and wetting agents to improve water and nutrient holding capacity.
Understanding your plants
The rate at which plants lose water through transpiration varies with the type of plant and location. If possible, choose low water use plants suited to your conditions and group plants with similar water needs (hydrozones), so you can water different parts of the garden differently, e.g. annuals, vegetables and pot plants may need shorter, more frequent watering by hand.
Millimetres, not minutes!
The local weather station reports how much rain has been received in millimetres, not minutes. 1mm of water (applied either by rain or irrigation) = 1 litre of water applied evenly to 1m2 (but 1mm of water applied to the soil’s surface will soak in further than 1mm).
The roots of most plants are located within the top 30cm of the soil. For Perth’s generally sandy soils, a 10mm “standard drink” per watering day is sufficient to ensure water is readily available for the plant’s roots. Overwatering may cause excess run-off or water to penetrate below the rootzone and be wasted.
Catch Cups to measure a 10mm Standard Drink
You can measure how long each sprinkler station takes to apply a 10mm standard drink using catch cups. Catch cups are available from Waterwise Irrigation Design Shops while stocks last.
A few things to remember:
- Watering before 9am allows plants to use water throughout the day
- Check and maintain your irrigation system regularly
- Don’t mix different types of sprinkler on one watering station
- Always replace like for like when replacing broken sprinklers
- For professional advice, contact your local Waterwise irrigation professional – www.waterwiseprograms.com.au
- Seasonal adjustments should be made to sprinkler run times outside of Summer months – see table below
- Remember to turn off your sprinklers if rain is forecast