Passion flower 'Duuk' blue - Hardy plantPretty as a picture! The aromatic 'Duuk' (Passiflora caerulea) attracts butterflies and insects. The perennial climbing plant brightens up our back garden. The violet blue colour of the flowers gives us a summery feeling! The flowers bloom all summer. The plant produces edible fruit in the second year after planting. The plant needs the support of a climbing rack or fence to grow. Pruning is not necessary, unless the plant becomes too large.