can we see the whole plant.. including the pot ... i barely see it there.. does it have a drain hole???

is the pot large enough ...??.. when is the last time the media was changed???

if the media failed.. and you have it in direct sun ... you could be sunburning it ... where are you.. big city name.. how intense ifs the sun???

ken

What have you been doing about fertilizing. The washed-out, yellow look (chlorosis) looks like a nitrogen deficiency, but should not be treated as such. It seldom goes well when hobby growers try to increase levels of a single or a couple of nutrients.

How long have you been caring for the plant? Does your pot have a collection saucer and do you allow the plant to sit in the water that collects there?

Al

Thank you for the replies. Here are the answers to the questions:

• I changed the pot about 5 or 6 months ago to a larger one. I kept the previous media and added more to fill the pot. I moved it to a larger pot because the roots were popping out and going crazy in the smaller pot and the leaves were drooping. After changing the pot, there were several new leaf growths and they are standing tall rather than drooping like before. There hasn't been any new leaf growths for about a month now.
• There is a drain hole and no saucer. I normally let it sit in the bathtub for a while after watering.
• I have the plant in a South facing window in Los Angeles. It gets very bright there, but I have the binds drawn until I wake up, around 10am. So it gets pretty bright light from around 10am - 1pm and then less intense light until sunset. Before changing the pot, I had it in a different room which only receives low light and it didn't seem to be getting enough.
• I fertilized the plant recently (2 weeks ago) with Jacks Housplant Special 15-30-15, but have only fertilized it once before this, maybe a year ago
• I attached a photo of the whole plant

to me that looks like a very large pot for that amount of top growth. But if you say the roots were popping out, so be it. Be careful not to overwater.

I give Fox Farm Grow Big to all my houseplants once a month. But when my Thaumatophyllum (formerly Philodendron) Tommy for short, gets a bit of yellowing, I give it a weak dose of Miraclo-gro Miracid. It seems to help.

The color looks decent on that 2nd pic, so those first closeups may very well be from sun damage too.

I'm in New England sun so my south-facing is quite different. My Tommy is about 6' away from a southwest triple window.

I would say experiment and observe. Move it a little further away from the window and see what happens. Try different foods. I think lower ph is called for in that genus. The Jacks food you mention is formulated for blooming plants (high middle number). The first number is geared to vegetative foliage growth.

Here's an interesting article about the Philodendron renaming.

https://www.house-plant-hobbyist.com/blog/2019/5/20/thaumatophyllum

Looks like overwatering to me.