Question
Several of my orchids were showing signs of not enough watering by the leaves (especially the phals) getting a little crinkly. I examined the roots and they were definitely getting dry and dying (not mushy and rotten).  I started to increase my watering schedule a little, and then, after a period of time, I started to notice a little green algae forming in the bark and mosses in the pot.  Is this safe or have I overdone it?  I only water once a week and soak the pots and allow to drain, but in Florida when it is really hot (they are in a greenhouse with fans and ventilation) I will water a little mid-week if they are really dry with no moisture left in the pot.  All the plants look fine and better than they did before, but I am not sure if this greenish formation in the pot is OK.  Help!

Answer
Hello Theresa,

Living in Florida, high humidity can be a problem which contributes to algae growth, especially on the moss.  I would suggest removing the moss and using only the bark.  The algae probably won't hurt your orchids, but it may not look very appealing to see.  

As temperatures rise you will need to increase watering the orchids in your greenhouse with such good ventilation and air movement.  While once a week was good during cool weather, you may have to increase it to 2, 3 or more times a week as temperatures rise above 90F.  

Although I have never had an algae problem with my orchids, I've heard that some persons use Physan (an algaecide) to treat their orchids.  If you use it, go easy with it as too strong a dose may harm the roots, diluted per the instructions it should be fine.  

Hope this helped.  

Jim Kawasaki
San Jose, Ca.