Beginner Gardening: What killed my Dieffenbachia?, 0 by captKirkS

captKirkS wrote:
I bought this Dieffenbachia about 3 months ago and have been able to keep it well. I watered it once a week misted the leaves once or twice a week. It sits next to a window and gets 5 to 8 hours of indirect light plus is sits directly (4 feet) under a large florescent fixture.

About a month ago, I noticed a leaf starting to die so I cut back on weekly watering and only watered when the soil completely dried based on readings from a moisture meter. I continued to mist the leaves once or twice a week though.

Two weeks ago, my brother came to visit. He noticed that almost all of the leaves were a light green instead of the dark green it should be. He said the soil was too dry and started watering it every other day or so. The last day he was here (9 days altogether), he also said the plant needed fertilizer so I put some Miracle Grow in the water the 9th day. I think I put too much MG in the water though. I also stuck a piece of banana peel in the soil. Within a week the plant started turning yellow and now looks like it does in the photos. I have removed dead leaves, let the soil completely dry-out then watered it with less Miracle Grow. It is steadily dying and has white spots on it.

Is there any hope for this plant?
If so, what can I do: more/less water, more/less fertilizer, more/less light?