Invasive sea holly

Hello....new to this site. I am trying to find out how best to control sea holly. Everything I seem to read on the internet is how to grow it. My problem is how to stop it growing. 2 years ago we noticed a few plants in the grass and thought them interesting. Now they have spread and spring up everywhere. We are guardian/gardeners for a large property in S.W. France and our boss likes to walk barefoot across the lawn to the pool and these plants are not very nice to tread on. We're digging them up in the walk areas but they really are everywhere now.

Any suggestions? We don't use any chemicals - completely organic.

Thanks,
Ken

 

Cover the area with weed suppressing membrane for a year or two / plant other things through it?

 

Thanks for the organic weed killer idea! Lovely. And I cannot cover the area as it is around the main houses and is lawn. We do use cardboard to cover all beds and then put BRF (chipped ramial wood) on top. No weeds and the plants love it.

 

Mowing the lawn is not killing the sea holly?

 

One good dose of weed and feed might just sort it out.

But nobody has to know.:WINK1:

 

Raining, finally, today so have had a good stroll around the grounds. The sea holly has really spread....everywhere. It obviously is not spreading through seed....root spread? I am really depressed as it is taking over and all my efforts to have a decent looking lawn is being undone. I think I may have to resort to some weed and feed product. Any suggestions? We're also talking about around 5 hectares of lawn so I would need a large amount....not a garden center small box of stuff.

Ta
Ken