Celosia plants are perennials in hot climates but can be grown as an annual in areas where the winter temperatures dip to freezing. Celosia plants grow in plumes, crests or spikes which look like jewelled feathers, wrinkly knobs or elongated cones. Celosia flowers appear in bright hues of red, yellow, cream, orange, rose, magenta and pink. The dwarf celosia grows 4 to 6 inches high while the tall forms can reach over 3 feet tall.
Celosia seeds will grow in nearly any type of soil, even heavy clay. It takes 90 days after planting for the celosia to flower in warm weather. The soil needs to have temperatures of at least 15.6 degrees C. If you do not have a long growing season, start your celosia indoors four to six weeks before the last spring frost. Sow the seeds in peat pellets since celosia do not like their roots disturbed. Cover the peat pellets with cling film and keep them in a warm place that stays between 21.1 and 26.6 degrees C. Remove the plastic every day to allow for air circulation. Mist with room temperature water to keep the peat pellets moist. Once the celosias have germinated in 10 to 15 days, move them to a sunny area.
Celosia will tolerate poor, rocky and sandy soil, but it thrives in rich, well-draining soil. Plant the seedling and peat pellet together in the soil in an area of full sun. Completely cover the root ball with garden soil. Space the seedlings 10 inches apart for the dwarf varieties and 16 inches apart for the tall ones. This gives good spacing for air circulation. When planted too closely, the celosia's growth is stunted and the flowers are smaller. Water well after planting to settle the soil and reduce transplant shock.
Cut the celosia flowers when they are fully opened. Cut them in the morning, after the dew has evaporated. Remove all the leaves from the stem. Wrap a rubber band around the stems of six to eight flowers and hang them upside down in a dark, dry area with good ventilation. After several weeks, the flowers are fully dried and will last six months without losing their colour. Use the dried celosia blossoms in flower arrangements, wreaths and swags.