Periwinkle

Not sure that this is the final solution but I think what I would do is , if you have cleared it as much as you can, then every time I see a young shoot appearing I would spray it with RoundUp or similar and just keep at it and inspect the area every few days and knock back the young shoots over the course of this spring and summer. Only time will tell if it works. I tried that method with ground elder and with some success.

I agree but a little tip if you get "Roundup" put a little baby oil into the diluted mixture and then brush it on the leaves, the oil will help it to stick on and be far more successful. For a small area, or for an area you wish to avoid plants you do not want to exterminate, I would be inclined to put on rubber gloves and use a paint brush and carefully brush it onto the perriwinckle leaves. If it is a large area with nothing else to spoil, then I would put your mixture in a pan and dip an old soft sweeping brush into it and brush it over the leaves of the area you want to treat but avoiding your special plants. This way you will rid of the mass of it and any that survive after the paint brush method should controle it. May seem a lot of effort but not so much heart break as fallowing the whole garden!

Sally I made the mistake of taking cuttings of this plant and it was almost everywhere, I tend to keep the bully in check by just digging it up when I see it taking hold.

Its not too much trouble now I can keep it in check with my normal weeding routine but then again I do like weeding! Hel.xxx.

You can get brush-on glysophate under the brand name 'Tumbleweed'.

Sandy, see my response to Hollygate today regarding ground elder. Should also work for periwinkle.