Sorry Spooky, I didn't pick up either that you were enquiring about Marigolds.
I grow african and french from seed from online seed merchants. Usually a good germination rate. The theory is scented marigolds deter insects and the french / mexican varieties roots exude something that deters nematodes - hence good for root crops (could be the other way round :) )
This year I'm also trying a rather extreme tagetes called Tagetes Minuta, not so succcessful in germinating but have some on their way now. They can grow up to about 6ft tall - not particularly pretty - but are meant to be very hostile to other plants, so I'm hoping they'll get rid of some mares tail and couch for us.