Question
Hi Jim,

This is my first orchid and I was painfully ignorant when I bought it. I've had it for 2 weeks and I have it in my bedroom with 50-60 % humidity, at about 75 degrees in a southwest facing window. When I bought it, it was potted in peet moss with shriveled puedobulbs but 4 spikes of beautiful flowers ( the reason I bought it!) I've watched as the leaves have begun to yellow and read as much as I could as to the care of orchids. I felt that it needed to be repotted asap, so I with a sad heart, I cut off the beautiful flowers and pulled it out of the pot. It has been trying to make some new roots, but the vast majority are rotten. I've cut them back  to about 2 inches long, sprinkled it lightly with root tone, and have it sitting in a tall clear plastic box on moist sphanum moss, partly covered with a plastic bag. I've also misted the leaves. Did I do the right things? Should I put it in a clay pot instead with bark? I have some soaking in water. Should I put rocks in the bottom of the pot for extra drainage?- it only has one hole in the bottom.

Thanks so much!
Lisa

Answer
Hi Lisa,

From your description of the Oncidium orchid, it sounds as though the rotten root problem had happened before you bought it.  Roots will rot when the potting mix is kept too wet, but it usually takes a month or more for that to happen and since you've only had it for 2 weeks you were not responsible for it.  My guess is that the store or nursery you bought it from watered it like the rest of their potted plants.  

Your growing conditions sound about right except for the southwest facing window unless it has sheer curtains.  Oncidiums do like quite a bit of light but that window is a bit more than oncs. prefer, that is unless you live near the Canadian border.  To tell if the light levels are okay, look at the leaf color for a hint.  Onc. leaves should be a light to medium green color when receiving good light, yellowish means too much while dark green means too little.  

Misting is fine to help maintain humidity but do not mist from mid afternoon onward as any moisture left on the leaves overnight is inviting a fungus growth.  You didn't mention if there was any air circulation where it is, all orchid plants like to have some air movement around them.  If possible, since they are near a window you might leave it slightly open -- weather permitting.  

With only one hole in the bottom of the pot, it would be a good idea to put about an inch of rocks in the bottom.  Once you notice some new roots growing, go ahead and pot it up.  

Hope this helps.  Good luck and good growing.  

Jim Kawasaki
San Jose, Ca.