105-112 days. Cocktail Series seeds easily grow classic and tidy begonias bursting with timeless 1 inch blooms. Begonias are native to the South American tropics and will thrive in a variety of humid and shaded summers across the country. Cocktail Series begonia seeds mature into dwarfed 8-12 inch mounded shrubs ideal for urban or confined gardening. Cocktail Series begonia is easy to grow from seed and a seasonal favorite for any decorative pot, planter, or hanging basket or just as popular keeping out in the garden. Pelleted Seeds.