On Gardener's World on 12th June, I heard Monty Don say that plants in outdoor pots may only need watering once or twice week. He said that they would perform better with a full watering occasionally rather than a drip watering system twice a day. Is this the case, as I have always used an automatic watering system twice each day.
How Often to Water Plants in Containers in Summer
Certified GKH Gardening Expert
Watering depends on some many things, type of plant, pot size, potting medium and soil, temperature, wind conditions.
You really have to check the soil and water as needed.
More water will be needed as temperatures rise.
Here is a great article.