One of the most determinant phenomenon in horticulture is the phenology of cultivated species, a factor that is poorly known for cacti. Sexual reproduction in the majority of species belonging to the deciduous tropical forest communities (including some cacti) takes place during the middle or the end of the dry season (Rzedowski, 1978). There is an increasing interest in the fruits of some columnar cacti with economic value in the national and international markets. Such is the case in the state of Oaxaca, Mexico of fruits of Stenocereus griseus (Haw) Buxbaum, locally known as “pitaya de mayo,” S. stellatus (Pfeiffer) Riccobono, “tunillo” or “pitaya de aguas” and Escontria chiotilla (Weber) Rose, “jiotilla,” species which produce fruits of economic relevance for several marginal communities in the state. The fruits of these columnar cacti are consumed fresh or used for making ice cream. The diversity in pulp color is an additional attractive of the fruits of the “pitayas” (Stenocereus spp.), which can be red, yellow, orange, purple or colorless, while those of “jiotilla” are invariably of red color. Several works have been made about the nutritional characteristics and diversity of the fruits of these cacti, mainly in their size and color (Ayala & Beltran, 2007; Benito et al., 1992; Pina, 1977; Beltran et al., 2005; Casas, 2005; Tenango, 2005). The objective of the present work was to observe the phenological behavior of these species in their natural ecosystem, in order to obtain information about differences in their reproductive phenology that could be used for the establishment of mixed cacti orchards in the semiarid tropical lands of Mexico.