Underside of Neo leaves (Kishu Ryokufu) turning reddish

[camille1585]

So this is a very very basic question, but Neos are still new for me. I noticed when watering the Neos this morning that one of the plants (Kishu Ryokufu) has some red/purple coloring appearing on the underside of most of the old leaves. My first guess was too much light, but the newer leaves don't show it, and none of my other Neos have it. I thought it might be related to the variety, but it was perfectly green when I got it early December.

To give you an idea, the plants are on a shelf in a south facing window. Until recently there was zero sun this winter (maybe a few hours a week), but the last 2 weeks have been relatively sunny, and they get direct sun from about 1pm to 5pm. (knowing that the light isn't that strong, the Netherlands is level with southern Canada). I also added a led light strip above them to supplement on cloudy days. As a note, none of my Phals, Paphs or other low light plants show high light symptoms.

Temperature is around 20-22°C during the day, and drops to 16-18°C at night.

I can take a photo later if it helps.

[Hakumin]

A photo will definitely help.

Overall though it sounds like natural pigmentation. Some varieties are more prone to it than others. High light could indeed be the cause, but sometimes even normal levels of light will cause excess pigmentation to appear in the winter as the temperatures drop.

Are the temperatures you measured the temperature of the room as a whole or those right at the shelf next to the window?

[Leafmite]

Red coloring is not usually a problem. Plenty of light, cooler temperatures or even a need for a little phosphorous can sometimes cause leaves to be reddish or purple.

[camille1585]

I took some photos when I got home, and the redness is not as visible and more mud colored than in reality. The temperature is measured on the shelf the Neos are on, and since it indicates the min and max, I see how cool it gets at night.

From your comments it sounds like it's normal, so I feel better! Just surprised that it didn't turn red earlier since the vendor grows in a greenhouse better lit than my window shelves!

[Hakumin]

Looks completely normal.

There are some varieties that also develop a flush of pigmentation specifically in the fall and spring too.

There are some varieties that combine variegation with that pigmentation making for pink stripes or pink new leaves.