I received my philodendron about 4 months ago and re-potted it with Dr. Earth potting soil. I keep it in an East facing window about a foot from the window. I live in Northern California in the mountains, where daytime temps in the house are somewhat chilly at around 55 degrees.

Within the past 2 weeks I have noticed these red ringed spots on nearly every leaf of the plant. I stopped using tap water and switched to room temperature rain water for my plant thinking that might have been part of the problem but now I'm concerned it may be diseased.

Can any experienced house plant experts out there advise me on what is going on, and what I should do?

Attached is a picture showing these spots.

Thank you in advance,

Kayla

Welcome, KaylaRTT!

I would check the underside for any bugs. If you don't see any, then the next question is, have you fertilized it at all? Wondering if it may be a calcium deficiency.

Hi Kayla, Welcome from me too!

My first thought was that the leaf issue might be due to temperature fluctuations but after googling and looking at photos I now wonder if it could be bacteria related? I found the following when googling; check out some of the descriptions listed and see what you think:
http://extension.psu.edu/pests...

You might want to post your photo over on the Aroid Forum: http://garden.org/forums/view/... to see if any of the more knowledgeable Philodendron growers could offer advice.

55 is really cold in my opinion,and philodendrons like it warm,but I think your problem may be Bacterial Leaf Spot.
Do you water form overhead,and saturate the leaves?
If so,that may be your problem,and I would keep the leaves dry at all times.