Q: What is this. Should I cut the canes to get it to grow back this year?
A: It is common dogfennel,Eupatorium capillifolium. I cannot decide whether it is a weed or an ornamental plant. I love the feathery stems that shoot straight up in the air. On the other hand, it was a hated weed in my father’s pasture because when cows ate it, their milk tasted funny. It does tend to scatter seeds rather freely but seedlings are easy to spot and pull up if you don’t like their location.
Actually, there is an ornamental variety called ‘Elegant Feather’. It is sterile and seedless so it doesn’t have seedlings.
If you decide you like it, cut the brown stems back the ground every winter before new growth begins in spring. The clump will gradually enlarge each year.