I hope that this information will help you. Basically nectar-rich plants attract butterflies. Plants like; Buddleia, A nettle patch (somewhere discreet for caterpillars) Bluebell, Honeysuckle, Hyssop, St John's Wort, Sweet William, Thyme, Yellow primrose, Grape, Hyacinth, Honesty, Candytuft, Ice plant, Helychrisum, Snapdragon, Sweet Pea and Lupine. There are of course, other plants the list goes on.