Not a weed at all, this wonderful plant is attractive to butterflies, bees and birds. A herbaceous perennial, which pretty much means not-a-shrub, it dies down completely in the fall and grows from the ground up each year. In my backyard (shown in photo) it goes from buds poking out of the ground in April to an impressive 6 feet tall and flowering by August through to frost. Hardy from zone 5 and up (in North America), it does well in sun to part shade. As you can imagine, for a plant that grows this quickly and with good size leaves, it is not happy in drought conditions–watering regularly will grow a robust specimen covered in flowers. If the height is intimidating, it can be pinched back in early summer before flower buds appear, and if in a windy location, it would be a good idea to support it. When considering it for a garden, establish it at the back of your garden border and allow for it to spread out at least 3 to 4 feet over a couple years in ideal conditions. Eutrochium can be divided in the spring if it becomes too big.
In addition to being an ornamental, Joe Pye Weed is considered a culinary and medicinal plant. Among its other folk names is Kidneywort and Boneset and was purported to be used to cure typhus in the 1800s. A search of plant lore on the internet or in the local library will provide more details on using the various parts of the plant.