By Pdb
Lancashire,
United Kingdom 
Please can anyone ID this.
I bought it a couple of years ago and wished I'd never set eyes on it. It's taking over. The roots grow horizontal and it's spreading!! Wish garden centres would put on the label that they are prolific growers.
It gets to about 4 FT with pink flowers on top.
Thank you
24 Mar, 2015
Answers
Agree with Landgirl, I suspect the original plant had this in the pot with it and it took over... Eradicating isn't going to be easy unfortunately.
24 Mar, 2015
Are the pink flowers followed by fluffy white seeds rather like dandelion fluff? If so make sure you don't let it seed at all or it will be everywhere if its willowherb.
24 Mar, 2015
Previous question
« This is a photo of the seed label from before sorry about the mix up
That looks like Rosebay Willowherb, which is a weed in gardens.
24 Mar, 2015