do magnolia trees require a lot of water?

Answer 1

Not really. No more than most any other tree like maples or oaks. I have one that's doing fine while we're in the throes of a pretty good drought.

Answer 2

The amount of water needed depends on the soil. The specifications for a magnolia tree are a moist, well drained soil. They also thrive better in an acidic soil, which can be obtained by using a pine or cypress mulch around the base of the tree. If your soil is sandy, you will have to water more often that if it is clay based.