Answer: The bulbs may be responding to differences in temperature, water, or lighting, or they may vary in quality. Newly purchased amaryllis bulbs of adequate size should bloom reliably within about six weeks from planting; however, if the bulbs were small they many need to grow another year to reach flowering size. (Premium quality bulbs may send up as many as three blooming stems over a period of some weeks.) All I can suggest is to provide the plants with bright light, keep the soil evenly moist, and hope for the best.
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