Hesperis Matronalis The Hesperis matronalis or Sweet Rocket is a Hardy Biennial which although short-lived, freely self-seeds in the wildlife or cottage garden. The charming tall spikes hold sweet-spicy fragrant lilac and purple flowers with a delicious evening fragrance in late spring. The Hesperis matronalis is very attractive to butterflies, moths, bees and other beneficial insects with its nectar-rich flowers. This is a must in the wildlife garden, seeding readily in drifts. Plant with Brunnera, Digitalis or ferns for a natural display. The plants are clump-forming. Height up to 90 cm, spread 40cm.