I agree with Christie. Just stop watering and keep out of direct light. Eventually the leaves will yellow and die back. As long as the bulb doesn't freeze, it will be OK. Sometimes the dormancy is very short in zone 8. New leaves appear within 2-3 weeks of removing the yellowed leaves. If you are not trying to get winter blooms, you can relax about forcing dormancy. Some cultivars never go completely dormant, but still put up some new leaves and bloom in the spring as the day length increases.
