I am desperately trying to care for the ctenanthe I have at my office but he is suffering and I cannot figure out why. I have a calathea in the same room who is thriving. The plant is not in any direct sunlight, he is not blasted by air-conditioning, I water only when the soil is almost dried out and allow all excess water to drain when I do. He had a dose of fertiliser and seasol a few weeks ago which looked like it helped a little, but the leaves are dull, they have lost the colour on the underside, there are yellowish spots in the leaves and I haven't seen any new growth for some time - I adore this plant but I have no idea what it wants!!

These are very difficult to keep in my experience. Has it always been in such a large pot? Feeding a stressd plant isn't a good idea.

I'd say toss it and replace it with something else!

I have several varieties of these plants at home and they all get on very well this one just seems to want to test me! I feed all my plants on a regular schedule - this specific plant has been in that pot for well over a year and has only started to show signs of stress in the last 1-2 months.

I'm too attached to give up on him just yet

I agree with Sue, although not necessarily about tossing it. A large pot is very difficult to water properly because the excess soil absorbs lots of water and retains it for a long time. I suspect that the roots of your plant have been slowly suffocating and the effects are now starting to show up. I don't recommend doing it, but if you were to unpot the plant, I think you would find a very small root system that is struggling to survive.

I do suggest that you remove all the loose soil on the surface that is not in direct contact with roots. This excess soil is keeping the soil in the root zone from drying out frequently enough. That excess loose soil is also misleading you as to the soil moisture around the roots. Once you remove the excess surface soil, you can then water as soon as the surface of the remaining soil is almost dry. Add just enough water so that it reaches that same level of dryness again in about a week. Experiment a bit to determine the right amount.

It does need protection from direct sun falling on its leaves, but it otherwise it should be as close to a bright window as possible. If it is more than 4 or 5 feet from a window, it is not getting enough light.

It needs just water and no other supplements.

Thank you WillC! I decided to go down the drastic route and repotted into a much smaller pot. You were totally right, his root system was very small and the soil at the bottom of the big pot was still very damp. I would guess it never fully dried out. I think the plant is going to get worse before it gets better but there was no evidence of root rot and the smaller pot is going to make it much easier to control the moisture levels so I am hopeful in time he will make a full recovery! Fingers crossed anyway

I appreciate your courage in taking the more drastic route. If it works, the plant will be all the better going forward. Keep us posted.