Calathea plants needs only moderate sunlight. Direct sunlight can damage its appearance as it can turn the leaf colorless. I think it is best to keep them indoors near a window that has transparent curtains to obtain moderate sunlight. This plant also needs around 60 degrees fahrenheit in terms of temperature and high humidity. You can use some humidifier if available or some DIY humidifier can also do the trick for best plant results. Calathea also needs frequent watering. We can say that these plants can be a bit sensitive to environmental factors but I am sure they are worth keeping. -
D.Tower
