Light Levels

• 1). Check the light levels for your orchid several times during the day. It may be receiving direct sunlight at some point that is causing sunburn. Sunburned leaves can be yellowish, have brown spots or brown margins.
  
  
• 2). Move your orchid away from windows with direct sun and any bright, incandescent lights. Put shear curtains over windows where bright sun shines through to help diffuse the light if you can't move the orchid.
  
  
• 3). Trim sunburnt leaves if they bother you and there aren't too many of them.
  
  

Fungal Infections

• 1). Sanitize leaf spots by gently rubbing them with a cotton ball lightly soaked in rubbing alcohol. Don't use too much alcohol, just lightly soaking the cotton ball will be enough to kill the fungus.
  
  
• 2). Avoid wetting foliage when you water. Use a watering can with a long spout to reduce the risk of getting water on leaves.
  
  
• 3). Thin overcrowded plants to improve airflow. If you have several orchids placed together separate them to allow wet foliage to dry more quickly and to help prevent spreading the disease.
  
  
• 4). Apply fungicide containing fosetyl-AL or manzecob. The Aloha Orchid Nursery recommends alternating products and spraying your orchid monthly to help cure and prevent fungal infections. Always read and follow the manufacturer's directions carefully before applying fungicide.
  
  

Mineral Buildup

• 1). Check for a white crust around the edge of your container. This could be salt build up due to hard water. Flouride, iron and fertilizer can also settle into the bottom of the pot and cause brown spots or brown tipped leaves.
  
  
• 2). Flush the pot with de-ionized water. Let water run from the bottom of the pot for a few minutes to ensure all mineral buildup is flushed from the soil. Flush your orchid pots monthly to maintain healthy plants.
  
  
• 3). Commence regular watering with bottled water or collect rain water for your orchid. Water thoroughly, empty the drainage dish 10 minutes after watering and water again when the potting medium is dry halfway through. According to Texas A&M University, phalaenopsis orchids should never be allowed to dry out.