I purchased an amaryllis bulb at Home Depot a few weeks ago. The very tip of the bud and some small leaves were already sprouting from the bulb. However, after a while, the leaves turned a dull brown-grey color. I watered it according to what was recommended and tried giving it artificial light when it first started, but nothing has stopped the browning. The plant is still growing though and the flower bud seems healthy. What is wrong? Does this have something to do with dormancy?