White Powder on Orchids

Growing Conditions

• Orchids need bright sunlight and warm, humid conditions in order to thrive. They prefer 40 percent to 85 percent humidity, according to University of Illinois Extension. Orchids also need daytime temperatures of 70 to 80 degrees Fahrenheit. They require a very well-draining planting medium, such as shredded bark.

Fungi

• The warm, wet growing conditions of orchids are just what fungi need in order to grow. The white powder you see on your orchid is most likely fungi growth. Fungal spores land in the soil or on the orchid and find the conditions to be just right for multiplying.

Solution

• Measures to rid orchids of white powdery fungi include wiping the plant with a damp cloth followed by application of a fungicide spray. If the potting medium is heavily infested with fungi, remove the plant from the pot and replant it in new, unaffected planting medium. Let the plant dry out a bit before watering it. The medium should be dry to the touch a few inches below the surface.