The importance of floral phenological synchrony among genetically compatible pollinizers and the main cultivar in an orchard requires a permanent evaluation of commercially grown and new introduced cultivars in all different locations where hazelnut is suitable for growing. Floral phenology of introduced hazelnut cultivars and two Chilean ecotypes used as pollinizers, were evaluated during five years (2007-2011), at Santa Rosa Experimental Farm, Quilamapu Regional Research Center, Instituto de Investigaciones Agropecuarias (INIA), latitude 36'31 degrees 34 '' S, longitude 71 degrees 54'40 '' W, Chillan, Chile. The earliest cultivars shed pollen by early or middle June; 'San Giovanni', 'Barcelona', 'TGDL', 'Tonda di Giffoni', 'Gem', 'Segorbe', 'Ennis', 'Pauetet', 'Mortarella', 'Ribet', 'Ghirara' and 'Ianussa Racinante', while 'Willamette', 'Montebello', 'Butler', shed by middle of June and most of them during middle of July and early August; 'Clark', 'Gamma', 'Lewis', 'Zeta', 'Santiam', OSU 504-130 and 'Delta', while 'Epsilon' starts shedding pollen by the end of July and early August. Stigma receptivity in the other side, in the earliest ones took place by middle of May; 'Negret', middle or late June; 'Mortarella', 'Amarillo', 'Barcelona', 'San Giovanni' and 'Iannusa Racinante' and middle or end of July; 'Ghirara', 'Butler', 'Verde', 'Pauetet', 'Lewis', OSU 504-130, 'Ribet' and 'Zeta', while 'Casina', 'Hall's Giant' and 'Butler' by end of July or early August. Finally, 'Willamette', 'Gem', 'Segorbe', 'Epsilon', 'Ennis', 'Clark', 'Gamma', 'Delta' and 'Pauetet' show receptive stigmas by middle or end of August.
