Many reasons, variable by plant species - boron/ calcium/ zinc/ copper/ molybdenum deficiencies, too much photo load, anoxia (lack of sufficient air in the soil), herbicide injury, several forms of viral infections, temperature, pH ....

What are you using for fertilizer? How old is the planting?

Al

Picture please.

Low humidity/dry air

Can t be low humidity dry air. It's been nothing but a sauna here for the past three months where I have the plant outside. I live in NJ, on the shore. I"ll send a pic.....

Does it get a period of darkness at night? Or is there always a light on it?

It's outside. normal laws of nature apply.

The pressure of garden fairies dancing on the leaves at night ? :)
Yes, a photo would be helpful.

Here is one....

A different leave....

Again: What are you using for fertilizer? How old is the planting? The object is to make available as much information as possible so folks can eliminate as many possibilities as possible and focus on the things it CAN be, From the start, I was thinking perhaps a Ca or B deficiency, and that's still what it looks like, but without more information your best hope is a bunch of SWAGs to sort through.

Al

I'm using Dyno grow, foliage pro, as per your recommendation. I'm not sure how old the planting is because I got the plant as a gift for a funeral that was held in Feb. of this year, so that's when I took control of the plant.

It was inside until the end of May and then it was placed outside under a large maple tree that gives it very bright but not direct sun. The leaves didn't start crinkling until about a month ago.

This post was edited by CJ-Speciosa on Sat, Sep 20, 14 at 12:25

The fact that you recently accquired it from a florist (I'm assuming), probably means that the soil is sub-standard for long term home growth.

Possibly, but it was putting out normal leaves a few months back.

quote from the link below: boron deficiency?
Watch for the following nutritional deficiency symptoms: Magnesium (Mg) deficiency, a problem with some cultivars, appears as golden-yellow margins on lower leaves. Prevention of Mg deficiency via supplemental Mg is much more effective than trying to reverse an Mg deficiency. Iron (Fe) and Manganese (Mn) deficiencies exhibited as reduced growth rates and chlorotic leaves can occur during winter months when the soil temperature is below 65ðF (18C). Sulfur (S) deficiency, exhibited as overall chlorosis of foliage, is sometimes seen when using highly refined, low sulfur fertilizers. Boron (B) deficiency may be a cause of longitudinal ribbing of the leaves, often seen on new growth.

Here is a link that might be useful: peace lily recommended culture