s/h and root rot
 

just switched all of my phals to s/h last week. Today I took a look at them and two of my plants have extensive root rot. Took them out. Cut the roots off and sprayed with physan and then cinnamon. Back to s/h.

Any suggestions? Have anyone else had some root rot since switching?

Rotting roots is absolutely normal when transferring plants to S/H. When roots grow, they grow tailored to the environment that are in. A root that grows in a dry mix, like bark, can't adapt to the overly wet S/H. That's why it's so important to repot orchids into S/H when there is brand new root growth (not just new green tips on existing roots). As those roots grow into the Leca, they will grow in a way that they are suited to all that wetness.

Are there any new roots on your phals? If there are, you could try putting the pot in plant in a clear bag to maintain humidity while the roots grow. If there are no new roots, then I'm not too sure what options you have.

Have a look at this website for some detailed information on S/H.
All about Semi-Hydroponics

i had new roots. They turned black and stubby. I cut them off. One of the phal is currently in bloom. The other one has a 2 ft spike on it. I just repotted them in S/h and hoping for the best.

Repotting into s/h while they're in flower or in spike isn't the best time, as they're concentrating all their energy on flowers at this time and not new root growth.

You said two had root rot, the others are fine?

You expect rots to root as Camille said if the roots aren't used to it.

yes, the rest of my plants are doing fine.. so far. Should I leave those two plants alone or should I put them back in bark?

If the roots have already rotted and they are in s/h I would wait now for new roots to start.You have to either way and going back to bark isnt going to speed up the new roots emergence I dont think.

A little Kln or Iba might help...or superthrive.My favorite so far has been some rootone type Iba mixed with a base like lanolin so it stays where you put it.

Yeah if the roots are gone and your humidity is OK it's as good in the LECA as anywhere. Expect to lose a leaf or two and get a few small growing leaves for a while, but it should recover in time and grow well in the S/H long-term..

Some bottom heat might also help to speed up the rooting process. A seedling heat mat works well for that.