Elfie,

Thanks a bunch for your help. I can very much connect with your advice about lack of sunlight. Whenever I put the plant near the window, I feel it becomes healthier, but for some reason, recently by reading other forums I got the impression that this plant should not need sunlight and it's better to be away from window (seems to be too far for me). I will try that!

Do you have other suggestions for keeping the plant humid?

You're very welcome Ghazal :) Its great that you've noticed it does better with more light, always trust your instinct as the generic advice online is hard to apply to so many different scenarios. Calatheas don't do well in direct sunlight as it can scorch the leaves, but in a north-west facing window it will largely receive indirect light and a small amount of weak sunlight when the sun is setting, so putting it next to the window should be great for it. As a tip for working out what is "bright, indirect light" try and find a place where your hand casts a fairly strong shadow, or where you can easily read a book without needing a light on. Direct sunlight is when the rays hit the plant.

In terms of increasing humidity, theres a few things. You can add a little water to the pebble tray but do not let it reach the bottom of the pot as you don't want the roots to be sitting in water. As the water evaporates, it creates humidity. Buying a humidifer is another option if you want to, although probably not necessary until winter. Or placing it in or near the bathroom or kitchen where it will get some steam if that's an option. Grouping plants together if you have others always helps to increase humidity.

Hope that helps! Also, in case you aren't aware - Calatheas are fussy about the minerals in tap water if you have hard water in your area. It's best to use distilled or rain water where possible, although I can't see any evidence of your plant not being happy with the water.

Hope you notice an improvement soon and do post an update if you remember, I'd love to see how you get on!

I believe this plant has been renamed and is not a calathea anymore

it's Calathea warszewiczii. it's still a synonym and is acceptable.

but it's now called Goeppertia warszewiczii.

the leaves droop like that from lack of moisture, either it's not getting enough water from underwatering or roots rotted from overwatering and it doesnot have enough roots to take in water.

it grows in clusters: after some time the cluster stops growing and a rhizome shoots off for a new cluster. it's best to keep several together, they prefer to be connected thru rhizome. the other shoot that died on you was probably an old cluster: it's normal for them to decline after some time.

but you should be seeing a new one come up to replace the old.

they resent root disturbance: so I would not down pot at this time: keep it as warm and humid as you can: preferably over 75F at all times. it would love 80-85F with like 85% humidity. at 65F it will stop absorbing water and go semi-dormant. it stops growing then and might drop leaves too.

oh and weak late and early sun is very good for it, so NW and NE is very good.

I grow my Calatheas in West window that is partially obstructed, but they still get dappled sun for a few hours till sunset and they really like it.

@petrushkaThank you so much for your guides, I always try to water as much as to keep the soil wet. Maybe sometime I overwater it. I'll try to be more careful about watering it.

Also, thanks for the correct name, the pictures in google are way more similar to my plant than Calatheas.

I see in the pictures of Goeppertia warszewiczii that some of them has flower too. Can that happen while the plant is indoor? Do you have a recommendation about using fertilizer? @Elfie @petrushka

you can use time release granules like 14-14-14 or 10-10-10 or any houseplant fertilizer. the idea is if the plant grows fast feed it more often, if the growth is very slow at all times in general feed it at half-strength or even quarter.

in my experience in good light indoors with some weak part time sun they are still slow. in tropics outdoors ;) that's a totally different game.

they do bloom outdoors in SO FL in very warm humid climate. some people do manage to bloom some other marantas or stromanthe (they are related), but I don't remember seeing pics of this kind blooming indoors. all factors are important: strong but diffused bright light very warm temps and high humidity.

it's just not possible to get that indoors.

@petrushka I see, thanks for your advice!

That plant grow best in bright indirect light, good air circulation, and with other plants nearby to maintain humid environment it's needed. That plant doesn't like loneliness.