Not Enough Moisture

• Lilies need to be misted periodically about every day or at least twice per week to keep them vibrant, especially when maintained as houseplants. The added moisture that misting provides prevents lilies from appearing limp and lifeless when the air in your home is dry. If you're unable to mist your lilies regularly, place their containers in a water-filled dish lined with pebbles. The pebbles help ensure access to humid and moist conditions, which lilies need.
  
  

Too Much Water

• Although lilies require moist, humid conditions to grow and develop, too much water can make them wilt and die. Propagate lilies in loose soil with good drainage. If maintaining lilies as houseplants, make certain their primary containers are set in trays where excess water can drain. Check plants within 30 minutes of watering, and dispose of excess water that has accumulated in the tray. Overwatering lilies can damage their roots.
  
  

Lily Leaf Beetle

• The lily leaf beetle invades lilies and consumes their flowers and leaves, which ultimately causes the plants to deteriorate down to their bulbs. The best way to prevent a beetle infestation is to purchase bulbs from trustworthy sources. Always take time to remove soil from the bulbs before propagating to avoid planting contaminated plants. Spray lilies with an insecticide in the late spring and early summer to guard against pest infestation.
  
  

Disease

• Lilies planted outdoors are especially prone to fungal disease. A diseased plant shows sign of wilt before it dies. Get rid of diseased plants to prevent the fungus from spreading to other plants nearby. Spray plants with fungicide in the spring as a preventative measure.