Abstract Flowering, peel growth and abscission provide examples of processes regulated by endogenous hormonal balance and susceptible of reacting to applied growth substances. Knowledge, accumulated during recent years, of internal balances and of reactions elicited by exogenous factors, has been integrated. Aspects of mode of action, dynamics of processes, the time component, non-hormonal factors and their interaction with internal hormonal balance and applied regulators are discussed in relation to application.