WHY DOES THIS HAPPEN?
There can be a number of different reasons why grey or black dry spots may appear on your plant. These include: the plant being sensitive to lime, overwatering and/or poor drainage, dusty leaves, fungus, or underwatering.
Too much water is never healthy for a plant, and so overwatering is often linked to poor drainage and also fungal problems in your plants. Make sure to check on each plant’s specific water needs - some plants prefer to dry out between waterings, whereas others prefer a certain level of moisture. However, it’s never a good idea to leave plants completely soaked and waterlogged for prolonged periods of time. Try to always follow Planta’s watering schedule and check the plant’s soil before watering again.
If you believe that lime sensitivity may be the problem, then it may be worth investing in a water purifier to avoid watering your plant with hard water.
Finally, regular misting/cleaning can help prevent dusty leaves from becoming a problem - if your plant requires this then Planta will let you know, as it is not necessary for all types of plants.