The factors controlling Dendrobium Jaquelyn Thomas flowering were evaluated using data collected from an experiment in which flowering observations were made over 5 years. The number of flower spikes per plant increased as plants aged, reaching a maximum at 3-4 years, and then declined. Flowers per spike declined as bud drop increased with aging. Spike length reached a maximum after 3 years and then declined to a length just above that produced by young plants. Bud drop was greatest in the coolest part of the year. The cyclic pattern of flowering with the lowest yield in winter became less pronounced as plants aged.Dendrobium flowering was apparently initiated about 4-5 months before a harvestable spike was produced. A negative correlation existed between daylength 4 months before harvest and spike yield. Minimum temperature in the 5th month before harvest was also significantly (P = 0.001) and negatively correlated with spike yield per plant, the number of flowers per spike and spike length. Solar radiation 3, 4 and 5 months before harvest was negatively correlated only with spike yield. Spike length was positively, and bud drop negatively, correlated with maximum temperature in the month of harvest. Short days in the 4th month before harvest and low minimum temperature with overcast conditions 5 months before harvest were related to Dendrobium flowering.