Calathea Musaica, just like the other members of the Calathea family prefer to be kept relatively moist which means watering them regularly. But regularly doesn’t mean choosing a specific day and sticking to it no matter what, it means reading when the plant needs watering and reacting to the plants needs.
With a Calathea you don’t want to let the soil become bone dry before you water it again or the plant will start to suffer. Instead stick your fingers in the top two inches of soil and when you feel it drying out water it thoroughly. It’s important that the pot has drainage holes as you don’t want the roots sitting in water but as long as they do the plant should be able to take a thorough watering.
If you struggle to gauge when your plant needs watering then you could try using a moisture stick. A moisture stick is a fantastic device that detects the moisture level of the water. The device has two metal prongs that you place into the soil, then you receive a reading, usually on a scale of one to ten. With the Calathea we would recommend watering when it is around three rather then waiting for the moisture in the soil to drop to one.
Through using the moisture stick over time you will be able to know when your plant needs watering and when it doesn’t and eventually you’ll be able to do this without the help of the stick. Many people can pick up their pot and feel by the weight when it needs watering as the plant will feel a lot lighter around this time.
It’s also important to know that you may need to water it less during the winter months and more during hotter spells so be aware that you might have to alter your watering schedule if you do develop a once a week habit.