Hello all, ...from Europe again :). I hope it is all right to revive this topic almost a year later. Helen, I hope your plant still thrives. I happen to have some problems with my Stromanthe that I thought were rather similar. I took some actions already, it is too early to see the results though. Then I read through all of the above comments and still not sure. I got my plant around a year ago, it was rather small, and grew rapidly. It did have some very little dry ends since the beginning, nothing major. This is how it looks now. Constantly growing new, healthy leaves, but it only takes a couple of weeks tll they all become so dry on ends. I did remove alot of leaves already. I keep the soil moist and mist leaves every day, sometimes even a couple times a day. I give it showers monthly. The humidity in my flat is usually 50%. For a long time I believed it was the humidity issue. Could it be just that? On the other hand I do have Calathea lancifolia (which I believe has similar humidity preference) and it is doing fine. Maybe there is something wrong with the soil, thought, since it was planted in all purpose soil. Yesterday I repotted into a slightly bigger pot. Got rid of most of the soil while trying not to mess with the roots too much. They looked very healthy but started to overgrow the pot. I made a new mix (sort of). Since it is very hard to get the basic ingridents here, for "base" I used store bought soil with Osmocote fertilizer and it said "super light" on the package. They do not give actual information on the ingredients here though. It only said it is a 'peat soil' and is reach with humus. I am defnitely no expert on soil, all I can say it indeed was light and soft to touch, maybe it had some peat moss in it (?) and some perlite already, not much though. This is how it looks like, different to what it was in before for sure. To that I added alot of perlte (around 40 %) and just a tiny bit of orchid mix. I planted the Stromanthe with this mix I made in terracota pot. I am not sure if I did the right thing with all that. The soil soaked up alot of water. I would be very happy if anyone could comment on that.

I have that Calathea as well, beautiful plant. Calathea "opens up" for daytime and "closes" at night. Mine moves most when it gets alot of water. I am curious what others will say about the spots. My plant also has a few small round spots like yours but I have no idea what they are. I thought maybe leftover marks after my long battle with mites or maybe a small sunburn caused by careless misting... They do not spread though, so I'm not that worried, but it would be good to know how to avoid it. For watering I usually use tap water as well, just not straight from the tap. If possible, I let the water stay in a can overnight before I use it for watering. I don't know if that is good or necessary but my Calathea is doing fine and I have it for 2 years. I definitely agree on the drainage hole. A pot with a hole is a must.

Check the underside of the leaves. By what I see in the in the pics (whitish stippling on the upper surface) I bet you'll find tiny white bumps, like grains of very find salt on the undersides which is the classic sign of spider mite infestation and the sudden deterioration and leaf browning also go with the territory.

Melanie, if you suspect a nutrient deficiency (have you fertilised? how long have you had it? what soil is it in?) then try a complete balanced liquid fertiliser - I use Dynagro FP. If that's the problem, you won't fix the damaged areas but it shouldn't get worse and new leaves should come in okay. Calatheas are notoriously picky. About everything. They need humidity, bright indirect light, no drafts and moist but free draining soil. Their thin leaves are quick to show problems. As far as pests go, they can get spider mites which are tiny and hard to see, but I don't think that's the problem here. Beautiful leaf pattern!