During the growing season, the soil of your Venus Fly Trap should be kept damp at all times. Depending on pot size and how hot and dry it is where you are located, this may require watering your Venus fly trap daily. Venus Flytraps should be watered when the soil is just barely damp and should be watered to the point where the soil is thoroughly saturated then allowed to dry to the point of being just damp before watering again. In the summer months, this can happen in just a day, if the pots are small and the weather is very hot and dry. But most of the year, it’s usually 2 to 3 days between watering and sometimes as long as a month goes by in the winter months between waterings.
When Dionaea are dormant, their soil should be kept just moist, not exceptionally wet. The rule of thumb is that then you touch your finger to the top of the soil, just a few specks of peat moss should stick to your finger and it shouldn’t feel wet.