Why do tips of plant leaves turn yellow?

Besides dry air, there are some other reasons why plants can develop brown tips and leaf margins. Some plants are sensitive to the fluoride and chlorine in tap water. Spider plants, Ti plants, and Spathiphyllum are most commonly effected by fluoride, developing brown leaf tips as a result. Excess salts from fertilizer and water can also cause leaf tips to go brown. Occasionally, accumulated salts need to be leached out of the soil. To do this, apply large amounts of water repeatedly, to dissolve the salts and wash them out the bottom of the pot.