Question
Hi,
i have alovely calathea it is giving lots of new leaves but the have brown spots on 1-3cm whan fully opened.
it took me a long time to get the watering correct a small cup every 3-4 days and i feed once a month.

any ideas?

Answer
Dear Emma, Calatheas are pretty difficult to grow, so there could be several reasons for the brown spots.  The main reasons are low humidity, fungus infection, and over fertilizing.  Calatheas need high humidity, higher than inside most houses, so it is recommended to grow them over a tray of pebbles with water in it (but never standing in water), and to mist them daily.  The lack of enough humidity will cause the leaves to curl on the ends and turn brown.  Over fertilizing will also cause calatheas to turn brown on the edges.  Ideally, they should be fertilized at half strength and fertilized infrequently.  I would probably cut the fertilizing in half or a third to make sure it doesn't get fed too heavily.  Also be sure to water as soon as the top surface is dry to make sure they get enough moisture.  The last possible reason for the brown spots on the leaves would be a fungal infection, and this would probably appear as true spots, roundish and perhaps starting off yellow or sunken in appearance.  In that case, you should spray with a fungicide.  I'm not sure what fungicides are available to you, but if you have limited choices, you should be able to find NEEM, which works for insects, mites, and fungus and is an organic compound. Be sure to remove the infected leaves as they will not heal and may only spread disease.  Good luck, and let me know if you need further assistance.  Melissa