I think I know the answer but....

bobloes

I am a volunteer with Age UK and I 'do' gardens for the less able.  A couple have recently moved in to a house with an established garden and part has what I am pretty sure is vinca planted.  Unfortunately the area has a membrane covered with bark chips.  The vinca has sent out runners but few of them root because of this.  The result is a mess of tangled runners with isolated 'plants'.  I have never grown vinca so am I right in my assumption that it is unlikely to produce the ground cover for which it is normally (I am guessing) planted?  If I am correct then I intend to force some of the runners through the membrane in order to produce the required result.  Any comments gratefully received.  Cheers.

Obelixx

I think you need to identify suitable stems and pin them down at a point where you then make a small corss in the membrane so they can set roots.  Like you would strawberry runners in wee pots.

Lupin 1

Vinca will provide some ground cover, depends if it major or minor Vinca, but both spread very easily and need keeping under control.  Unless you can guarantee to keep helping in the garden I wouldn't encourage it. Maybe the membrane has been put down to suppress other things, bit drastic to have been put down just to stop Vinca.

granma

Vinca usualy roots quite easily . cut  off 6 inch lengths making sure you remember top from the bottom . add to a jar of water  after removing about 3 inch of the bottom leaves. it wont be long before you see the roots forming from where the leaves have been removed . When the roots are about 1 inch long just layer them under the bark chippings . you may have to weight them down with pebbles  untill they get established . Take note : the varigated one is very vigourus and does get all over . The plain one is daintier

bobloes

Thanks all.  Your comments seem to confirm my thoughts.  I shall be talking to the owners to see how they want to proceed.  Cheers.