Question
i know i over fertilized my orchid. i think its a dendrobium. i notice my leaves turning yellow. so i decided to repot. i notice all the roots are dark and there was a white crust on one of the stem. what should i do? please help me!

Answer
Hello Maricel,

Overfertilizing is easy to do with dendrobium orchids as they do not require lots of it to grow and bloom, in fact, too much can cause keiki or baby plantlets to grow rather than blooms.  

When you unpotted it to look at the roots, did you try gently squeezing them while running your fingers down them?  If you did, did the thin coating over the roots slide off?  If it did, that probably means that root was rotten.  To check whether there are any live roots, remove as much of the potting media from them then wash them with water.  Live roots will appear to be white or greyish while dead rotten ones will be brown or dark in color.  Remove the rotten ones and repot into fresh orchid potting media.  It probably would be a good idea to clean the old pot and reuse it.  Do NOT put it into a larger pot as dendrobiums love to have their roots confined in as small a pot that can just hold the roots.  

Hope this helped.  If you have other questions or would like more information about the above, write back.  

Jim Kawasaki
San Jose, Ca.