They bloom in May and June.

In northwestern SC (Zone 7b), _Gelsemium sempervirens_, the South Carolina State Flower, commonly called the "Carolina jessamine," blooms in March and April during azalea, wisteria, and dogwood season. It blooms a little earlier than that on the Coastal Plain. There is, however, a fall-blooming, scentless relative, _Gelsemium rankinii_ that would give you an extended blooming period--but no heady fragrance. Woodlanders in Aiken usually has the 'rankinii' in its rich horticultural inventory.