In order to stabilize strawberry production in summer and autumn in the Tohoku region of northern Japan, we investigated the effect of intermittent long-day treatment on flower induction and vegetative growth in everbearing strawberries. The results showed that the number of leaves on flowering branches tended to increase when 24-hour daylength treatment was performed every two weeks compared with continuous treatment. We found that ‘Natsuakari’ plants flowered continuously and developed leaves on branches appropriately under a 16 or 20-hour daylength after long chilling. On the other hand, we found that ‘Tochihitomi’ plants did not require long-day treatment for flowering after chilling. ‘Natsuakari’ plants exposed to two weeks of a 24-hour daylength followed by two weeks of natural daylength did not differ in flower number or yield from plants treated with a continuous 24-hour daylength.