I have some French marigolds but they keep dying. Can you help please? I have paid out three times for marigold plants but for some reason they keep dying. What can I do to stop this?
This article goes over basic marigold care: https://www.gardeningknowhow.com/ornamental/flowers/marigold/growing-marigold-flowers.htm
If you don't think there is anything cultural that is killing the marigolds, there might be some disease in the soil, or some other problem with the site. Try growing something else in that spot.
You can also try to get some analysis of the soil. http://mastergardeners.org.uk/get-involved/find-your-nearest-master-gardener/ will give you some assistance with that.