Question: what are hardy perennial plants?
Answer: Sedum. Sedums, also known as Stonecrop, are superb for their late summer and autumn colour, often flowering into November! ... 
Rudbeckia. Rudbeckia are reliable and popular perennials, valued for their long-lasting, splash of colour in late summer and early autumn. ... 
Geranium. ... 
Phlox. ... 
Japanese Anemone.