The effects of seed age on shoot regeneration potential and transformation rate of ‘Duncan’ and ‘Flame’ grapefruit cultivars, along with ‘Hamlin’ sweet orange cultivar were investigated. Shoot regeneration potential of all three cultivars varied throughout the season. Cumulative data for shoot regeneration of explants incubated in bacterial suspension exhibited higher values early in the season and in the first months of the spring, with significant drops during the winter months and later in the season. Transformation rate did not vary as much as shoot regeneration potential. Data describing the propensity of ‘Flame’ and ‘Hamlin’ tissue for genetic transformation exhibited a negative trend as the season progressed. ‘Duncan’ transformation rate held steady during the season. Taken together, our results confirm the need for specific culturing protocols to be developed and used for different citrus cultivars at specific times to reduce variability of responses these cultivars exhibit to culturing conditions and transformation attempts.