I think I've found a good way to keep track of watering plants. It's nothing fancy, just a chart to jot down the date when each plant if watered and the rainfall, an easy task in Arizona. Then it's easy to visualize the next time the plant needs watering. Below is part of the 2004 chart.
Here are links to blank forms if you want to try this technique:
January to June
July to December
Punch here to go back to the Garden page