Starting out!!

Marigolds are normally good for keeping pests away generally but that isn't the kind I found mentioned elsewhere...
http://www.plantcultures.org.uk/plants/marigold_grow_it.html
"Another marigold species, Tagetes minuta is distinct, being a very large plant with tiny flowers. It is usually grown by organic gardeners for its beneficial properties on soil, as the roots exude chemicals which repel couch grass and eelworms."

and http://www.thecuttinggarden.com/html/DataCard.asp?cat=2&type=halfhardy&Product=343

"Not a looker, but an extraordinary plant - its roots kill perennial weeds. Its cleared a whole bed of bindweed at Perch Hill. Give it a try."

http://www.edirectory.co.uk/chilternseeds/pages/moreinfo.asp?pe=DBFBCJGFQ_+tagetes+minuta&cid=211
"It is not as an ornamental that it is sought, but for its reputation as a destroyer of weeds by means of its apparently herbicidal root secretions. Among the more popular weeds said to yield to these are Ground Elder, Couch Grass, Convolvulus and other nasties. "

Maybe it's just all rumours though   I know in companion planting marigolds are suppose to keep pests away from tomatoes etc, but I can't find out if it's pot marigold/calendula or african/french marigolds. I'd not plant the above marigold as edging on a bed, though, as they apparently get up to 4-8ft tall...