You have to dig it up and dig it up and dig it up, Sorry but that is the way you will eventually get rid. It will keep reappearing but eventually if you keep at it I found you win.

Thank you for input Drc726, I was hoping for a lazier way of getting rid of them. Some years I was plagued with lily of the valley in a small plot and it took me 3 years to get rid of them. I eventually succeeded by removing the topsoil and riddling it. I am definitely looking for an easier solution

Sorry John no easy solution in this case just dig, dig and dig again...

Montbretia grow from corms. Unless you can get rid of every corm, it will come back again

...it even manages to grow through weed suppressing fabric!

Indeed it does 2 layers too.

Why do we dislike plants that obviously love us so much?

In my case doesn't fit into our garden - keeps appearing from next door!

A bit like the kid next door's football - grrrr

Yup!