I got a griffinia bulb in November. it was in bloom when I got it, but quickly died back to the ground. I thought I had lost it, but I dug it up and the bulb was there, roots intact. ive kept it on a seedling heat mat since and got a new leaf in February, but the insulation came off the window it was sitting in and a cold draft killed the leaf. now its not doing anything. I keep it moist and on the heat mat but nothing happens. the bulb looks healthy and the roots are still there, but no top growth whatsoever. any advice?