Where do you live? What kind of soil is it in? Did you mix the soil yourself? Last fertilized - how often - with what? Are you able to water thoroughly so water freely flows from the drain hole each time you water?

Al

Dear Toni, Al,

Many thanks for your answers. I'll try to answer them in order, starting from the list of Al.

I live in Southern England. About 14 hrs of light a day these days.

The soil is standard John Innes Nr. 1 (typical British off-the-shelf mix for growing young plants).

Fertilization- I use Miracle Gro slow release tabs, I put the required amount for the pot size in February.

I can water without any problems- the soil drains well, and I take care of watering until the water flows out of the drain hole.

About Toni's questions:

The curling leaves are the old ones, they curl on both sides along the length (like in an involute vernation). When I refer to the new leaves being a bit crackling, I refer to those growing according to the usual convolute vernation of Calathea (or Stromanthe, or Ctenanthe for that matter). Incidentally, these curled up leaves also seem not to fold up at night as much and as efficiently as the others- like the mechanism for pulling them up which is in the pulvinus is "damaged".

Indeed, this particular plant has been sitting in the same spot as the whole winter. I see what you mean about the leaves getting brown at the edges: this is exactly what has happened to some of mine! So it may be *too much light* that causes it?

About temperature and humidity, we live at an almost constant humidity of about 60% (at this very moment it is 64%). And the temperature is 18-21 degrees (Celsius).

I don't fertilize my Marantaceae too much- they're slow growers anyway. And no, I did not repot, or do anything strange. My watering routine is standard- I actually use an hygrometer and water when needed (only, I had to attend my father at the hospital recently and somehow I slacked a bit). I mist all my plants needing misting two times a day, in the morning and in the evening.

Toni, your suggestion that it may be too much light seems to ring a bell- I have moved the plant a bit to the center of the room now, let's see what happens. Indeed, there seems to have been a bit of discoloration in the leaves, which may be bleaching caused by too much light.

Once again many thanks Al and Toni, I'll keep my eyes open and I'll do my best. All the best!

Calathea, sounds like you're doing everything possible..Soil, humidity, watering.
Like I said, Cals and relatives are not the easiest plants to care for, some harder than others.
See how they do in less light. But remember, now that they're in lower light watch the watering. It may not need the same frequency as it was in the sunnier spot.
Trim brown edges leaving about 1/8" of brown on. Also, perhaps saving a container filled with room temp water 'may' help..Good luck, Toni

From this: "I use Miracle Gro slow release tabs, I put the required amount for the pot size in February." I'm left wondering if you added these tablets to the soil?

Al

I did put the tablets in the soil, at the depth suggested on the box, yes. They're the cone shaped ones made of yellow granules. Many thanks, C

Hello all, I live in karachi, Pakistan. I'm very new at gardening and can barely understand some of the terms used in your conversation. I am having similar problem with my cal as calathea did, except, I did notice one thing. Of late, the leaves start to curl almost immediately after the plant has been watered. I do water the plant twice a week. It receives filtered light The temperature these days is touching 40 degrees (centigrade). I am watering as much as I was when the temperature was in the low 30's. Am I underwatering? Please help!!

Shoabi., there are so many factors that affect how long a plant takes to dry, it's impossible to say from the info we have so far if your plant is getting too much or too little water. Picking up the plant should help you gauge how dry (or wet) it is. In your location, (assuming the climate is desert,) low humidity may be stressing your plant more than either of these. A terrarium might help. Adding a pic would be helpful.

At those temperatures Calathea tend to curl, will also do it with too much sun, especially if humidity is very low. Just make sure the potting mix stays moist without being soggy. They need good drainage. Mine also do that in hot weather but it doesn't seem to affect them badly long term.

Thank you for the response. The humidity here is up at 60-70% presently. I don't think thats an issue. i don't think drainage is an issue either as there is no water left standing in the tray. I make sure that the excessive water is totally drained. There are a few new leaves sprouting as well.

On our hot days the humidity can range from 90% in the morning to 30% in the afternoon, all in the one day. The Calatheas feel it most in the afternoon, then come good as the humidity rises back up.

What is the ideal humidity for calatheas please? I live in a generally humid climate but because of recent drought it's only about 50-60%, lower over night. I recently separated a plant in to new pots, have put them on pebbles, they're next to a steel louvre window which I slightly open during the day to let air and a tiny bit of light in, but I'm having the same leaf browning problem. One, as well, is not opening properly and seems weak and soppy. Not over watering, but misting one to 2 times a day. Would love some feedback? Sorry to hijack the post! Just thought it was along the same lines... :)

Where are you getting your humidity readings from? Relative humidity (RH) goes lower in the day as temperature rises and then goes higher into the night as temperatures drop. You may not be getting accurate figures. RH indoors can be quite different to outdoors, usually drier. But also, indoors it can become complicated from cooking and use of bathrooms, not to mention heating and airconditioning. Do you have photos you can upload to show the problem?