Watering is something that can make or break a garden. It is also something that new gardeners tend to overdo. I'm asked constantly "Why aren't my veggies ripening?" This is followed by surprise when I tell them to stop watering their gardens.
Now, don't get me wrong, watering can be crucial. I water several times a year. I don't water daily.
It's crucial that seeds and seedlings have a moist environment to start off in. It's also crucial that you make them work a little for the water. They need to be kept moist to stimulate germination and rooting.
After they've rooted nicely, you want to do deep, infrequent watering. I know that your first inclination is to water them daily because it's dry. What the plants want is to be watered every few days deeply. They need that water to penetrate a few inches into the soil. Plant roots go deep searching for food and water. If you water every day, they won't develop those good deep roots that are crucial to a healthy and productive plant.
You also need to be aware of the disease that too much water can bring. Those of us in the Northeast can well remember last year's tomato debacle. Once blight was found, it probably wouldn't have spread so fast if it wasn't for all the rain. In fact, this year there was blight found in a few places, but because of the dry weather, it stayed under control. The same can happen with over watering.
When you water, mud splashes up from the ground onto your plants. The mud can carry spores onto your plants that will cause disease.
This time of year, I tend to stop watering altogether. The fall beds that are just getting started will get a bit of water, but the rest of the garden is done. We'll have frost in a few weeks and I want the fruit that is already formed to ripen. I'm not looking to develop new fruit. If the plant has a little water stress, it's more likely to put all of its energy into ripening existing fruit. That is what we want in August and September.
Lastly, the best way to ensure that watering will be the most effective, is to build your soil. The richer your soil, the more organic matter like compost and manure, the more it will hold onto water in the first place. Mulches such as straw can also be helpful for cooling the soil and retaining water.
I water more frequently in the spring, slow the frequency in the summer while adding mulch and completely stop in late summer to force maturity of fruit.