Posted: 29/04/2015 at 08:44
I agree with all the above, but, they all answer only part a of the question, 'a) get rid of them' but an equally important part is 'b) a way to stop them coming through again?'
Well it depends on the type of patio. Properly laid patio's should have no cracks or spaces in between for weeds to grow into. If it it slabs, then it sounds like the sand and gravel underneath has failed and you need to relift them with a crowbar and level them off, removing any weeds as you do. Make sure the slabs fit tight against each other or use a patio concrete to seal the gaps and set the slabs.