Cephalaria gigantea (Giant scabious):
Very tall wavy stems topped with large lemon yellow scabious-like flowers. Easy to grow. May need staking or support. Hardy. Up to 2m.
Phlomis tuberosa 'Amazone':
Tall spikes bearing whorls of pink spikes in mid-summer. Hardy. To 1.5m
[Collect Only]
Verbena bonariensis:
Tall, airy but strong slender stems with flat heads of purple flowers in mid to late summer. To 1.8m. Frost-hardy.