Question
I recently bought a Calathea Mia at a garden show and I do not know how to take care of it.I love its big,emerald-white leaves and delicate pink flowers.The way the whole plant closes at night is just amazing-I haven't seen anything like it before!
Please give some tips on how to keep it healthy for a long time.
Thanks for your reply.

Answer
Hi Agustin,
  Calatheas are members of the Marantas family (Prayer Plants, Stromanthe and Ctenanthe are also Marantas). Marantas grow on the floor of the rainforest so they like a moist, warm and humid environment. Marantas fold up their leaves at night, like praying hands, giving them their common name, Prayer Plants. Plant biologists call these daily cycles circadian rhythms.

All Marantas require soil that is constantly moist. That does not mean wet or soggy soil. Lightly water these plants frequently and never allow the soil to dry out. When the top 1/2 inch of soil feels dry add just enough water to moisten the top 1/2 of the pot. Marantas are very sensitive to the fluoride, chlorine and mineral deposits found in most tap water. Water softeners contain a lot of salts that can also harm Calatheas. I recommend using distilled water. By using distilled water you can also avoid other problems that are typically caused by water quality. Misting plants with distilled water will also prevent those white spots left on leaves by salts and lime deposits in tap water.
Marantas grow best in low to medium light with little or no direct sunlight and will do very well under artificial plant lighting.

Marantas are very sensitive to being over fertilized. Only fertilize Marantas when needed and use only 1/3 of the regular strength called for in the mixing directions on the fertilizer package. Liquid fertilizers are best. Dilute liquid fertilizer 1 part fertilizer to 2 parts distilled water. It is also recommended that you ' flush the pot' about 2 weeks before fertilizing again. To do this pour enough distilled water into the soil so that it runs freely out the drainage holes in the bottom of the pot. Once most of the water has drained out repeat 2 more times. Wait about an hour then check the drainage tray under the pot and pour out any remaining water. Do not let the pot sit in standing water. 'Flushing the pot' can also be a quick fix for most plants that have been accidentally over fertilized.
 
All marantas need lots of humidity. To help increase humidity place plants on a tray of pebbles filled halfway with water. Grouping several plants together help raise humidity. Each plant puts off moisture and by grouping them together each plant can enjoy the moisture put out by the other plants around it. I have also found that regular misting helps a great deal.

The most common problem with Calatheas (all Marantas) is brown tips and edges. This can be caused by low humidity, improper watering (too much), Fluoride or poor water quality and too much direct sunlight. By making sure the plant has proper care this can be easily avoided.

Because of their colorful foliage, low light and high humidity requirements Calatheas are ideal for terrariums and indoor dish gardens. Calatheas do NOT do well outside.

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