I planted a pineapple top about 2 months ago. It has developed roots and the leaves or spikes on the bottom and middle of the plant are strong and green but the small spikes emerging from the core are brown and dried up and are easily pulled. Is my plant dying? I only water it when soil becomes dry and I mist the plant occasionally. I have it in a south facing window because it's winter right now where I live, so I put on the grow lights after the sun goes down to provide more light. Could this be "heart rot"?