Abstract: The phenology and growth research of a naturalized genus may offer information on phenophase threshold, thus providing references for evaluating adaptation potential. We observed the flowering season of 9 Viburnum species and the growth dynamics of 2 Viburnum species in the Beijing Botanical Garden. We analyzed and discussed the response of flowering season in acclimatizing to a winter-spring abnormally low temperature in 10 years and the mechanism linking vegetative to reproductive growth. The abnormally low winter-spring temperature in 2009–2010 delayed flowering in all Viburnum species. Delayed anthesis was attributed to the delayed heat in spring. The delay was closely related to the environmental condition of distribution sites in some species: V. opulus and V. burejaeticum, distributed in frigid temperate zones, showed the shortest delay times (10, 12 days, respectively), whereas V. macrocephalum and V. betulifolium, in subtropical zones, showed the longest delay times (21, 26 days, respectively). Pre-anthesis effective accumulated temperature in Viburnum was between 39°C and 368°C. The pre-anthesis effective accumulated temperature was increased or decreased among species after the abnormally low winter-spring temperature, which may be attributed to the different chilling-heat requirement of anthesis among the species. The linkage of vegetative and reproductive growth showed 2 forms: reproductive growth in early-anthesis species was strongly competed with vegetative growth, whereas in late-anthesis species showed effective supply, because vegetative growth in late anthesis can supply assimilates to reproductive growth immediately after the completion of flowering.