Another thing you can do to determine the amount of moisture in the soil is to use some type of probe. Whatever type of probe you use, the principle is the same: the probe is inserted deep into the pot among the plant's roots, twisted a bit, then pulled up....yes, it's just like testing a cake. Next you can run the tester between you fingers to pull off the soil, or pinch it out of the notches, and rub it between your fingers, to determine the moisture level. Many people...don't realize that the moisture toward the bottom of the pot can be very different from what's on the top.
A third method of learning about the moisture content is with a moisture meter. ... they can give incorrect readings if the salt level in the soil is high. When you pull the probe out of the soil, run it between your fingers! ...and in doing so, you can tell if the soil is wet or dry, and if the meter is working correctly.