Have just read an article in amateur gardening and there is a reply regarding mexican marigolds.
It says that mexican marigolds excretes chemicals from its roots that are toxic to horse tail ground elder,couch grass and many other difficult to eradicate weeds. it is stocked by chiltern seeds,bortree stile,ulverston,cumbria LA12 7PB tel 01229 581137
www.chilternseeds.co.uk.
Hope this helps someone
regards flower :)
From reading (no experience, sorry ;D ;D ;D), it's Tagetes Minuta, Giant Marigold?
All best - Gavin
yes gavin tagetes minuta looks like large african marigold