I would also be interested in the answer to this question. I've had one phal do the same thing. They split right down the center seam. Both sides of the leaf continue to stay green and healthy.

It happens, don't worry about it. I always figure its a humidity problem but doesn't hurt the plant.

Jane

Increasing the humidity of the Phal. will help. It won't heal the split, but it'll prevent the newer leaves from splitting. I accidentally let one of my Phals go too long without water and the tray below was dry of water too. the newest leaf began to split and ended up growing out that way too. I figured it was the lack of proper humidity, but I read up on it to make sure.

In house plants, splitting occurs when the plant has been allowed to go too dry, and then copiously watered. The plant cells can't handle the sudden influx of water. You can mend the leaf to prevent it from splitting further by making a butterfly across it with 1/4" green adhesive florist's tape. The tape is waterproof and will stay on for a very long time. I've had it stay on for as long as two years, until the plant discarded the leaf.

Wow! Great method! I'll try it if it happens to one of mine again.