Classic blooming bulbs for the winter holidays, amaryllis (Hippeastrum spp.) can grow outdoors in U.S. Department of Agriculture plant hardiness zones 8 through 11. In mild climates, you can plant them outdoors, although they need to be covered with mulch for the winter in USDA zone 8. In cooler climates, grow them in pots indoors.
When to Separate Bulbs
Remove the new amaryllis bulb from the “mother” bulb when the plant goes dormant in fall. Outdoor amaryllis go dormant naturally in fall. You'll need to force indoor amaryllis to go dormant in fall by following a set of procedures.
Potted Indoor Amaryllis
Set an indoor potted amaryllis in a somewhat dark, cool area, like the corner of a basement, at the end of September and stop watering it. The temperature should be between 50 and 55 degrees Fahrenheit. This will force the bulb to go dormant. Cut the leaves off 1 to 2 inches above the bulb with a sharp knife or scissors after they turn brown. Sterilize the knife or scissors first with household spray disinfectant and rinse the disinfectant off. Tip the container over and lift the bulb out of the potting soil.
Lift the “mother” amaryllis bulb from the garden soil with a shovel in fall. The leaves will have withered away by this time. Cut any remnants of leaves off 1 to 2 inches above the bulb using sterilized shears or a knife. Push the shovel into the soil 6 inches away from the bulb, making a circle all the way around the amaryllis to loosen the soil. Work gently to avoid damaging the bulb. Push the shovel in again and lift the bulb with the tip of the shovel.
Separating the Bulbs
Brush the soil away from the bulb, making sure you don't damage the roots. The new bulb will be growing on the side of the “mother” bulb. It will look similar to the main bulb but will be one-fourth to one-third of the size and will not have any roots. You can usually pry the baby off, but you may need to cut it off. Use a sharp, sterilized knife to cut the smaller bulb off. Replant or repot the mother right away.
Caring for the New Bulb
Pot up the small new bulb in peat-based potting mix in a 6-inch diameter pot that has drainage holes. The top one-half of the bulb must be above the potting soil. Set the container in a bright room but not in direct sunlight. Maintain a temperature of about 60 F and keep the soil lightly moist, not soggy. Be careful not to overwater because the new bulb has no roots and will quickly rot if the soil is kept wet. When the new bulb sprouts, or begins to grow leaves, move it to a warmer, sunnier spot.