Very seldom will you go a whole growing season without having to water your trees, plants, flowers, or lawn at least once.
The main thing to remember when watering, is when not to do it. Do not water during the hottest part of the day. That would be between the hours of 11 am and 5pm for most people.
If you water duing that time, most of the water will evaporate before the plant gets much benefit.
There is some debate on whether it is best to water in the morning or in the evening. My preference is for the evening. The sun is going down soon so the water has more time to soak into the soil and feed the plants.
Another thing to remember, is to make sure most of the water is reaching the roots. For flowers and garden plants that means watering at the base of the plants.
I have read that you do not water the leaves, that it’s bad for the plants. I disagree with that. Why? Because when it rains, the leaves get wet. I just think that you can’t use a harsh spray when you water the plants. Use a gentle spray, like a soft rainfall. And if you are using a watering can, water so it gets right at the roots.
If you are watering trees, you need to water right around the dripline. Watering to close to the base of the tree can cause the roots to go bad.
The dripline line is right under the leaf canopy.
One more thing to remember about watering: watering too often can lead to a shallow root sytem. If your plants don’t have to extend their roots down too much to get water, they won’t.
I recommend no more than once a week up to a few times a week in extremely hot, dry weather.