This rather unprepossing plant is Tagetes minuta, a half hardy annual and presumably a weed in its native Mexico, which is reputed to kill the roots of my nemesis, Aegopodium podagraria or ground elder. I heard about it by chance in comments on a Facebook page and decided to check it out on the interweb. Sure enough, even the sage Sarah Raven sings its praises and claims to have cleared a bed of ground elder with it. I have ordered a large packet of seeds for a few pence which will be incredible value if it really works.
According to those who should know, the plant has herbicidal root secretions which destroy the roots of perennial weeds such as ground elder, lesser celandine and couch grass. It is apparently 2.5m tall with finely cut foliage and small creamy yellow flowerheads which are unlikely to turn heads but who cares! If it gets rid of the ground elder and celandines in my prize herbaceous border I don’t care how ugly it is just as long as it doesn’t kill all my other plants as well.
I will make this one of my summer projects with regular updates. I would be very interested in your comments about this subject, particularly from people who may have tried it.