Question
I have quite a few phalaenopsis orchids and never had split leaves before. All of a sudden I noticed that most of the plants have at least one split leaf.What causes it and how I can treat the problem?
Thank you so much for your help.
Sincerely,
Emma

Answer
Emma, it is likely that you have a salt imbalance in the leaves.  If you have not repotted in the past year, consider doing so. I have found a dynagrow product called "Protek" to be helpful if you follow the directions exactly.  You didn't mention what kind of water you use and how you fertilize (ie type, concentration, frequency) and whether or how you leach.  If the leaves that split are floppy or stiff could also be helpful in the diagnosis.  The former suggests inadequate amounts of calcium and/or magnesium while the latter suggest too much or failure to leach.