The most famous red Amaryllis. Galaxy Group. Plant the bulb halfway into the potting soil. Use a large pot with an opening for water drainage. Heat is mainly needed for the development of the stem, so place the bulb at room temperature. Give the bulb little water until the stem emerges. Once the bud and leaf appear, the amaryllis needs more water daily. In winter, it takes about 6 to 10 weeks after potting before the bulb blooms.