Grasses can make superb specimens for large pots where there form can be really appreciated. They are mostly pretty drought-tolerant, rarely suffer from pests and diseases, and never need more than annual haircut. Here are of three of my favourites which can rival the best flowering shrubs when in bloom:
Stipa gigantea, the golden oat, forms elegant arching flowering stems up to 1.5m or more, gently swaying in the breeze above a neat clump of greyish evergreen foliage.
Miscanthus sinensis ‘Zebrinus’, the Zebra grass, has green leaved banded with horizontal cream stripes. The plume-like flowers appear in late summer and go on well into the autumn. In a 30cm pot, you can expect to reach about 1.5m.
Pennisetum alopecuroides 'Hamelin' , the fountain or foxtail grass, form neat mounds of mid-green leaves and becomes smothered in hairy bottlebrush like flowers from late summer until the frosts.