Seedlings turning yellow after replate.

[HeyMrDeej]

As the title says, I recent did a 2nd replate of a C intermedia cross that I had sown a little over a year ago. And some have turned yellow and some haven’t.

For background, they were originally sown in p723 at a 6pH if I remember correctly. Replated in p748 with a pH of 5.5 and same thing with this 2nd replate.

Was it because I disturbed the root system? Late in the season because it’s almost winter? Possible pH imbalance? Just unlucky?

[Dorchid]

Member Bluecrab found P748 to be a bit hot and runs it at half strength. As you’re replating from it, it’s possible the pH of the new batch wasn’t quite the same. I run it as well with a target pH of 5.3 and have only seen it slow one cattleya cross down but no yellowing. The other factor there is it was a protocorn/extremely small plantlets replate and it may just have been too soon for them to move to the new medium.

[HeyMrDeej]

Do you supplement any agar since you half it?

[Dorchid]

Yeah, you would need to add agar to achieve the same gel level as full strength.