Plants and fluoride

6. Browning of leaf tips: Low humidity, excess fertilizer, water that is high in fluorine, spray damage from pesticides, unfavorable soil reaction (a high or low soil pH), air pollutants or root loss due to excessive water in the soil will cause tips to brown. Water that contains fluorine should be allowed to sit for several days before using so the that the fluoride may bubble out. Simply trim away brown tips with sharp scissors to improve the looks of your houseplants.

Bubble out?