Summary Flower bud opening of gladiolus spikes in response to gibberellic acid and sucrose as influenced by water stress was studied. Water stress conditions were caused by dry storage of the spikes after harvest for 24 h. A pulse-treatment of the spikes with sucrose immediately on harvest allows opening of all buds after a subsequent 24 h period of dry storage, when transferred to water. On the other hand, spikes that are first stored dry and later pulse-treated show an obligate requirement for gibberellic acid in addition to sucrose. A similar requirement is shown by spikes that have been cold-stored for one week. The results indicate that the gibberellin requirement of spikes on dry storage is a consequence of the sensitivity of flower buds (in which the outer bract has not separated) to water stress which causes a disruption in the endogenous GA supply system.