Why would the leaves on your plant turn yellow, you might ask? The answer, typically, has something to do with water. Yellowing leaves can be a sign of moisture stress that is associated with either over-watering or under-watering.
With potted indoor plants, it is important that you water according to the plants’ needs. Too much or too little can cause the leaves to yellow. To gauge the thirst of your plants just touch the soil. If it feels dry, like bone-dry, add some water. If it’s very wet or even moist, loosen the soil and allow it to dry out.
Another sign a plant isn’t receiving enough water is when leaves begin to drop. Plants will do this to prevent it from sweating or transpiring. Before the leaves fall, though, they will turn yellow which is your heads up that the plant needs some water ;).
Too much water can also be damaging to the leaves and will show similar yellowing signs. In such cases checkout the stem. Over-watering can cause blackening. If the soil isn’t able to drain or breathe, the root system of a potted plant can literally drown. Roots cannot survive without oxygen.
Cold drafts on tropical plants will often cause the leaves to turn yellow and drop. Constant cold temperatures cause browning or transparent spots. If you notice any of these symptoms on your tropical plant, check and see if it is near an air-conditioner vent or a drafty window. If so, just move it to a place where it isn’t exposed to the cold air.
Plants age. As they do the lower leaves will turn yellow and drop off. This is a normal part of the plant’s life-cycle and is not cause for concern. This is especially apparent with ferns, pothos and Dracaena varieties. For some simple maintenance, don’t be afraid to just pick these leaves off your plant.
Leaves may yellow if the plant isn’t receiving enough light. Try putting your plant in a place with better light or try rotating it occasionally to even out the light distribution.
If your plant isn’t getting the nutrients it needs, its leaves may begin to yellow. Try adding some fertilizer once per month to supplement the plant’s nutrient needs. Also be sure to regularly flush the plant with water to leach out any mineral accumulation from tap water.