Water and sunshine are the two main things plants need to grow, give them the right amount of each along with a favorable environment and they will thrive.
The trick is learning how much of each!
A moisture meter will help you know what level of moisture is left in the soil so you can be a better judge of when to water. This meter works perfectly for us; the probe is long enough 7.5 inches works for most plants, the easy to read dial measures from 1-10, dry to wet.
Test the soil in two or more spots in larger pots to get a true reading over all.
If you'd rather not stick your pretty nails in the soil you definitely should use a moisture meter instead!