I have ground elder in one of my borders- as a novice gardener two years ago when I first noticed it I hoped it was just another plant i didn't know but was corrected when I realised it had spread significantly and did a bit of googling!
Last year I tackled it as much as I could by hand- it is an established border with large lilacs, shrubs, perennials etc. It was time consuming but it kept on top of it for a whiel. I used roundup gel but found it ineffective- I dont want to use chemicals due to lots of wildlife in the garden.
Am I ok to continue tackling by hand or is the only way forward to dig everything that I can up (I would have to leave the trees and lilacs) cleanup the soil and cover for a period of time?