Cambria leaves splitting

[Fiona]

My Cambria is developing fine brown lines along the older leaf veins, which then split. The one split is now almost the full length of the leaf. Could it possibly be to either over watering or over feeding. It has finished flowering, new growths are starting to develop, dark green. I am feeding a weak solution of 18:18:18 every 2 weeks, rain water every 5 days, depending on the weather, we are heading into our summer. Photo can be seen in album.

[Zoi2]

Sounds like your humidity might need to be increased.
Joann