One gibberellin is gibberellic acid, a natural hormone that can be readily extracted from common plants. All three control, stimulate, inhibit or alter a plant's development to one degree or another, depending upon the external environment. Gibberellins are noted as the most powerful of the growth promotors because they , increase internode spacing, induce and promote flowering in many plants, and modify the flower sex expression in some plants. Gibberellins are well known to promote uniform growth through cell enlargement. They cause plants to grow tall and elongated, with light green leaves, and also stimulate seed germination and other growth phenomena such as early flower formation.
Some plants initiate flowering after having undergone exposure to a period of cold.
In nature, these cold-requiring plants usually flower in spring or early summer, after having been exposed to the cold temperatures of winter. In other plants, flower formation depends upon day length or photoperiod. Typical gibberellin responses include larger blooms, stem elongation, flower stalk elongation, and in some cases earlier flowering, which are all desirable elements to commercial flower growers. Higher concentrations will result in adversely tall and weak flower stems. Gibberellins are popular with commercial growers to replace the cold treatment or long night treatment of plants such as azaleas to induce or force flowering.