|Some of my housplants get curled leaf tips and yellowing leaves with brown spotting. Could this be overwatering and/or overfertilizing?|
|Yellow leaves can be sign of many things, including underwatering, overwatering, too much sunlight/heat, lack of nitrogen, or salt/fertilizer burn, to name the more common ones.|
When leaves brown around the edges, the problem is often salt burn. Salts in the water and in fertilizer build up over time. Browning usually occurs on the old leaves first. This excess salt accumulates in the leaf edges, where it kills the tissue and the leaf dries out and turns brown. It's important to water deeply and slowly. At least once a month, water deeply enough to "leach" or push salts well below the root zone. Frequent, light "sprinklings" allow salts to accumulate in the top layers of soil, where the roots are, which is bad news. Similar symptoms occur when too much fertilizer has been applied. Always water plants thoroughly before and after applying fertilizer to help prevent burn.
Also, if plants are in too much direct sunlight, foliage can yellow and then turn brown, as it is basically "burning."
I'd start by flushing your plant with water under a hose or faucet and let the water run out the bottom to leach away possible salts. Then examine the plant's environment for appropriate lighting and watering. I'd hold off on fertilizer for a month to see if there's any improvement. Hope this helps!