Peace Lily problem

I have 4 small Peace Lilies, all part of one original parent purchased in 1987! Apart from leaf tips tending to go brown on the older leaves, I have had no problems. However, all 4 (which are not all in the same room so don't socialise together) are showing the same issue. Some of the leaves are folding in on themselves along the central spine. The newest leaves seem fine and only 2 or 3 others are affected on each plant. They are not dry. The leaves doing this are perfectly green and feel well hydrated.

Any thoughts?

 

Have they been recently split from the parent and potted up? They might be concentrating on growing new roots, at the expense of supporting the older foliage. I'm assuming they're neither too wet nor too dry at the roots? Or maybe a reaction to high temperatures?

 

It could be due to over watering or soggy compost. I let mine dry out completely before watering them and sometimes they even wilt, but I never keep the soil too wet.

 

Not been split for 18 months. I let them completely dry out between waterings. Usually I do them once a week, but in this hotter weather, maybe every 4 days. That's been their routine for yrs and I've never encountered this folding syndrome before. The odd thing is the affected leaves seem fine in every other respect - firm, consistent green colour, not floppy, no signs of infestation or virus.

Weird!

 

Have they got a little warm in this recent heat? A lot of plants curl their leaves to stop transpiration

Beat me to it

 

Possibly ... though they have managed much hotter summers than this before now. It has been pretty cool down here till today, but I noticed the problem a couple of weeks ago.

 

On further investigation it seems the central spine of the leaf has thickening slightly and almost become two ridges, though these are still firmly joined to each other.