If there's one plant you just have to have for the late summer garden, it's Sedum Spectabile "Autumn Joy".
This wonderful plant loves the sun and will bloom from late August right through to the first frost. The plant produces large, flat, burgundy flower clusters that positively glow in the low summer light. Autumn Joy is a good plant for edging around shrub borders. It will grow to a height of about 1' and does well in all gardening zones.
Plant Autumn Joy in well drained soil and don't overwater or it will rot at the base.
Seldom has a plant been more aptly named: Autumn Joy will give you years of joy in your garden.