The effects of GA3 on petal blackening in lotus depended on the time of the year. In tests in November, December, and March a delay of blackening was observed. However, in tests in May and September no effect was found. These data indicate an effect of temperature and rain. In Thailand the dry and relatively cool season occurs from November to February–March. The hot and rainy season starts in April and ends in October. A detailed investigation through the year was not carried out using cytokinins, although one experiment with TDZ pulsing in August showed a delay of blackening by only 0.5 d. It is therefore possible that the effect of cytokinins also depends on the season.