Most gardens like to have about one inch of rain every week. Some weeks you may get a lot more than one inch and some weeks you get way less. For the weeks when it is dry, you will need to water your garden. Also, keep in mind that clay soils dry out slower, needing less frequent watering than sandy soils that dry out fast and need to be watered more often.
To find out how much rain your garden gets in a week, make a rain gauge. Take a clean soup can with the top cut off. Put the can out in the middle of your garden. After each rain or watering, use a ruler to measure how deep the water is in the can. If the water you measure adds up to one inch or more for the week, your garden is okay. If not, you'll need to water to make up the difference.Record the amount of rain each week in your journal.