I installed a drip system in Atlanta and you will vary the amount of gallons per hour dependent upon the type of plant you are watering. Of course, larger plants such as shrubs and trees will require more water than smaller plants. All that being said (written) everything will depend upon the amount of water pressure from your source.
You can purchase kits that have as many 4 different drip head rates....you can also buy heads than can be adjusted to whatever drip rate you select. You can also install "sprays" and "soakers".
You are definitely going the right route, because you are putting the water where it will do the best good without losing it into the air as will typical lawn irrigation systems.
