Question
Hi, I bought a moth orchid two weeks ago.  It didn't say what kind it is but it has yellow flowers with bright pink spots radiating out from the center.  It had one slightly shriveled aerial root when I bought it but now several of the other roots have shriveled up.  What causes that? So far the rest of the plant looks healthy but I haven't owned it very long. I have been watering it about once every 7 to 10 days because it's winter here in New Zealand. I'm worried about over watering my pot plants because at the moment as the house is quite cold and damp especially at night.

Answer
Hello Grace,

What you probably have is a phalaenopsis orchid as "moth orchid" is one of the names it is often called.  

Aerial roots that dry out are usually due to low or lack of adequate humidity around them.  Roots need moisture to stay nice an plump.  Once they shrivel up they are basically dead roots, although parts of the root within the potting media may still be alive and well, just the exposed portion is dead.  

With winter in New Zealand, it would be a good idea to keep it in a nice warm location where there is some light air movement present.  Water when the potting media becomes barely moist, this is especially important when the weather is cool to help prevent root rot due to the media remaining wet for too long a time.  Water only in the morning.  

Hope this helped.  

Jim Kawasaki
San Jose, Ca.