Seeds of Dianthus barbatus alba white Sweet Williams, Poets Pink or Sweet John. Dianthus barbatus ‘Alba’ is a pure white form of Sweet William, absolutely beautiful especially when massed, They flower all summer from May to August, and they are intensely fragrant with a delicious rich perfume. Grows equally well in sandy to clay soils. Growing 12-18″ tall and 8-12″ wide. Hardy to zones 2-9 in full sun.