I have this dieffenbachia and it has really gone downhill lately. It has taken on a yellowish tint and the edges on most of the leaves look like they are drying up or are burning. It stays inside all the time and gets some filtered light through the patio door. I only water it when it gets on the dry side about once a week. I mist it occasionally and haven't fertilized it in about 2 months. I think I used too much miracle gro plant food when I fertilized it when I got it also about 2 months ago. Anyone got any ideas how I can get it healthy again? This plant is definetly not as easy to grow as they say it is.