Color: Yellow Flower Size: 1-2″ (3-5cm) Flowering Period: June-Sept Mature Height: 15-20′(4.5-6m) Pruning Group: C Planting Aspect: Sun/ Partial Shade USDA Zone: 3 Foliage: Deciduous Fragrant: Yes Price Group: Standard About Tangutica Golden Harvest Selected at the Boskoop Research Station in Holland, we have found this hybrid to be far less aggressive than the straight species. Golden yellow 1-2″ (3-5cm) nodding flowers are displayed against a nearly black stamen from mid-June through September. Attractive seed heads follow. Mature height 15-20′(4.5-6m). Pruning group C.