i don't know if they sell these where you live, and im not sure the exact name of it, but im sure you can get one at any garden shop...it's like two metal rods with a little box on top that tells you how dry or moist your plants soil it, it also reads the ph (except the ph reader on mine is broken)

i don't water everyday, i just check the soil every few days and when it's on the dry side i give her some water = )