Most hollies are evergreen, and most are hardy to about 0°F (USDA zone 7). Deciduous hollies are hardier, generally to about -20°F (zone 5). Although temperature limits are a useful guide, other factors, such as summer temperatures and rainfall patterns, also influence adaptability. Therefore, all the evergreen varieties listed here are noted as either "N" — northern, including the Plains and midwestern states east of the Rocky Mountains; "S" — southern, including the Gulf Coast and upper South; or "W" — western, including the Pacific Northwest and West Coast.

All hollies are dioecious, meaning that male and female flowers are born on separate plants: The berry-producing flower is on the female plant and the pollen-bearing male flower is on another. Only females produce the colorful berries and to do so require pollen from a male plant of the same species. Hybrids are pollinated by males of either parent species. Those few female hollies that produce some berries without pollen from a male plant are noted in the descriptions. Birds feast on all holly berries but prefer red ones over other colors.