Watering from taps – city water contains too much fluoride. Allow water to sit overnight before watering.
Shallow watering – allow water to flow freely out of pots
Low Humidity – air is too dry, mist plants every few days
Too much fertilizer
Too much water leading to plant root rot
Not enough water
Chemical burn
Plant diseases
Direct sunlight
Nutrients Deficiency (phosphorus, magnesium , iron or calcium)