The author summarizes gibberellin structure-function relationships and practical applications in forestry.First, the gibbcrellins are described as a group of diterpenoid acids, and its activity appears to be related to the degree of oxidation of the C-20 func tion irrespective of hydroxylation at C-3 and C-13. Hydroxylation to the C-3 and C-13 form (e. g. either GA1 or GA3) may be very important to obtain a highly biologically active GA in vegetative growth of the shoot.Secondly, gibberellin metabolism is derived from acetyl ccenzyme A and all CAs originate from a common pathway leading to GA12 aldehype.If we want to control flowering by adding exegencusly a /florigenic/ GA, we should have a knowledge of the endogenous GA and their metabolism. Then ,we can design experiments and treatments to ’synergize’ of the exogenously applied GA.Finally, some metheds arc shown how to induce precocious flowering and how to enhance flowering in conifers. The extra flowering effect of applied GA4/7 is also synergized.