Question
i brought home a calathea, and without reading the tag, i stuck him in the DIRECT sun for about 5 hours.  I burned his leaves pretty badly.  is there anything i can do to save him now???

Answer
Hi Maggie,
  There is nothing you can do to save the burned leaves. Damaged leaves will not heal. The only thing you can do is remove the damaged leaves as long as there are not too many of them. If there are a lot of them (more than 1/2 - 3/4 of the total amount of leaves) then the best thing to do is to remove the most damaged leaves, up to about 1/2 of the total amount of leaves, then remove the rest of the damaged leaves one at a time as new ones grow.
While the plant is recovering, put it in a place where it will get lower to medium light with absolutely no direct sunlight. Be careful to water it properly and do NOT give it any fertilizer. Fertilizer should never be given to unhealthy plants anyway. Fertilizer will not cure an unhealthy plant and could actually harm the plant. Calatheas are especially sensitive to being over fertilized when they are healthy so giving fertilizer to a stressed and unhealthy Calathea will only harm the plant. When the plant has mostly new, healthy leaves with few (or none) of the damaged leaves left and has lots of new growth on it then you can lightly fertilize the plant. I recommend using 1/3 of the amount called for in the directions on the package. Dilute 1 part liquid fertilizer to 2 parts distilled water. Liquid fertilizers are best but if you are using a powdered fertilizer then mix the fertilizer according to the directions on the package then dilute it as recommended.

This plant will likely recover, depending on the type of Calathea it is. Most Calatheas (as well as other members of the Maranta family, especially Prayer Plants) seem to actually do better after a heavy pruning. Most of the time they are able to recover from damage that would likely kill another type of plant and grow back even bigger and healthier.
I once cut down a Prayer Plant to re-root it as cuttings because it had stopped growing well. I had no intention of trying to save the plant so I cut it down completely, only leaving a couple of scraggly leaves. I was going to throw it out but instead I had set it aside and forgot about it. Two weeks later I noticed it and it had lots of new growth. In a relatively short amount of time the plant grew back even bigger and healthier than it was before.

Unfortunately recovering from this incident will take some time and the plant will not look very good for awhile. Fortunately these plants grow pretty quickly so it should not be a long time before this plant is full, healthy and beautiful again.

I hope this helps. If you have any questions or need additional information please don't hesitate to ask.
     Thanks
       Tracy