Why do candle wicks sometimes mushroom?
The mushrooming occurs when the candle consumes the wax more quickly than the flame can burn the wick. Trimming the wick will alleviate this problem. Extinguish the candle, trim the wick and relight. Do not allow the wick trimmings or other materials to fall into the wax pool. It is recommended you trim the wick to 1/4 inch before lighting it each time.