|I have noticed a rust colored deposit that forms on the top of the soil in my houseplants a few weeks after I have planted them. It does not seem to affect the way they grow, but I'm not sure what it is or what I can do to get rid of it.|
|It may be mineral or vegetable in nature - either mineral depostis from your tap water or a mold that grows on the soil surface. To determine if it's mineral in nature, put some water in a clean saucer filled with sand or stones next to the houseplants. If the orange deposit forms as the water evaporates, then it's some kind of dissolved minerals from your water pipes. If nothing is left behind then your soil is nurturing more than your plants!
Mold and fungi growth are signs of excess moisture and can be controlled with better drainage or reduced watering. Filtration or water treatment will remove most minerals from your water supply.