ABSTRACT
The garden zinnia (Zinnia elegans Jacq.) has been one of the most popular garden plants for many years. Zinnia elegans is an erect annual with sessile, cordate-ovate opposite and entire leaves. The leaves are approximately 4 to 10 cm long and 2.5 to 5 cm wide. The flowers are borne solitary and have broad showy rays which usually become reflexed. The disc is usually yellow or orange, but is very nearly absent in double-flowering forms. The majority of research related to flower induction has been conducted on Z. elegans and this chapter deals with the flowering process of Z. elegans. Growth regulators have been used mainly as growth retardants on zinnia. The two major growth retardants effective in controlling height are daminozide and ancymidol. The extra light intensity received during later sowings was not enough to overcome the short days flower initiation response of this species.
