There about a dozen species of Weigela and many hybrids and cultivars (Hillier lists 26, many of which were bred in France.) There are several examples of the genus in Belfast Botanic Gardens. The two illustrated here are a commonly grown variegated form Weigela florida ‘Variegata’ and a large flowered, deep pink cultivar. 
All the species are from temperate E. Asia where they grow in moist rocky woods. Weigela florida was introduced by Robert Fortune in 1845. Many of the cultivars have awards of Garden Merit.

Photos taken in Belfast Botanic Gardens in May 2019. Copyright: Friends of Belfast Botanic Gardens.