Cosmos flowers come in brightly colored single or double flowers which include white, pink, orange, yellow, and scarlet colors. Rich, fertile conditions are not necessary to grow yellow cosmos. Yellow cosmos is not a heavy feeder. Excess fertilization will cause plants to produce excessive leaf growth at the expense of flower production. Yellow cosmos is a sun – loving annual; it will not produce as many blooms if grown in the shade.Cosmos will perform best if grown in well-drained soil.