How can I control my Jerusalem artichoke?
I purchased what I thought were 5 Helenium 'Morheim Beauty' from a local nursery a few years ago! They were planted in April and I knew by July that it wasn't the right plant as they were 3m in height. I have an enormous border so they actually look rather well, however several people have told me that I will never control them as they spread quite quickly.
Will they become a problem?