Did it rain a few days ago and you can’t remember when or how much fell? Maybe there was sufficient that you don’t need to water tonight? The app helps you make this decision.
The SGW schedule tells you how often to water; the duration of watering is calculated to give your garden an effective 10 mm dose of water – this is the optimum amount (allowance is made for the impact of mulch, soil type, slope, etc.). If you look at the iPhone app’s rainfall plot you will see a 10 mm line marked to help you compare how much rain has fallen in comparison to a 10 mm dose. This is a rough guide only, as not all of the rain will make it into your soil, but it can help you to make decisions like these:
"I water every 5 days and was due to water tonight, but I see that we had 12 mm yesterday – I’ll skip the watering"
"I am watering once a week and I remember we had several days of rain a few days ago. But I see that it was only a mm or two in total – I will still water tonight"
"It’s January – hot and dry – and tonight is my weekly watering night. It dumped a summer shower last night – but only 3 or 4 mm fell in my area. I’ll do my regular watering tonight, but cut back the duration a bit."