I water early morning and evening,this gives the water time to sink into the ground before the sun comes and eveaporates it.Also if you water in the hot sun,this will leave water on the plant causing a burnt,boiled plant.
I water in the morning only before the sun gets to warm, plants seem to flourish in the humit air like a rain forest, so when the sun warm up the garden after a cool watering the plants them self asorb the moister not just the earth, not every garden is the same, it's location, time of day of full sun and the number of hours of the full sun, will also play into when and how offten to water.
The standard rule is 1" of water per week. Depending on soil conditions; whether the ground has clay in it or if it is all sand, one may have to water more or less frequently. Water drains right through sandy soil but not clay. Also different plants need more water when they are producing like cucumbers- to be more tender.
Another thing to know is that the roots will grow deeper the deeper you water so some people only water once a week. Look for clues from your plants; if the leaves drooping they may be asking for water. So if the ground only gets a sprinkle every so often the roots tend to stay up near the top of the soil line. It is fun to pull out the roots in the fall to see how far the roots went. Also mulching will help retain water around the roots. Adding compost to the soil when preparing the beds adds water retaining humus to the soil. Growing a cover crop and tilling it in in the spring will do the same.
The authors are the women in the program. If you would like to ask a question, go to the Ask a Question page.