Dig out plants first or just use tiller?

[MotherOfGodWeeFella]

We've got a large sloped bed which has spread onto the lawn over time. There are lots of perennial geraniums and it's encroached on the grass by about half a metre - it was like this when we moved in. I'm going to sort it out this year and have an electric tiller. Can I just use that and pick the remains of the plants out prior to levelling and putting grass seed down or do I need to get the plants out before using the tiller?

The soil is quite heavy with clay and we've had issues with rain pooling in certain places so I'm thinking we might need a French drain between the bed and the grass too. There's something similar on the other side of the lawn.

It depends what plants are growing there, if there are dandelions and bindweed for example, every cut bit of root could make a new plant.

Since it sounds as though you are going to need to put some drainage in you might as well do the job properly and dig out the plants properly. If it’s mostly geraniums they are likely to be in clumps so that will make it easier. Shame to bin them though, any chance you can pot some of them up to give away or donate to a plant sale.

Thanks viques - it's purely hardy geraniums and there's a bit of another perennial that I've forgotten the name of along with some bits of grass. I've done so much digging out of things this year already that the thought of doing more isn't a great prospect!