Abstract The physiology of dormancy in Lilium longiflorum ‘Ace’ was studied by determining the relationships between plant growth and composition and treatments such as bulb scale removal, cold treatment, field soil heating and chemical stimuli. Initiatory activity was continuous in the daughter bulb until its anthesis, but elongation of daughter axis leaves and internodes were normally inhibited until autumn. Inhibition of the daughter axis was high during the spring prior to anthesis of the mother, but progressively decreased following anthesis and disappeared completely by autumn. Balances of inhibitor-promoter growth substances were found in the bulb scales. Daughter scales were found to be the principal source of inhibitors. Treatments conducive to breaking dormancy included 40°F storage, GA 3 treatment and field soil heating in early spring. Dormancy-breaking cold treatments were followed by changes in nitrogenous substances characteristic of dormancy removal in other species. The period of dormancy in the daughter portion of the lily bulb is of the correlated type and involves scale inhibition of axis elongation rather than initiatory activity in the apex.