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.
Himalayan balsam (Impatiens glandulifera) has rapidly become one of the UK’s most invasive weed species, colonising river banks, waste ground and damp woodlands. It successfully competes with native plant species for space, light, nutrients and pollinators and excludes other plant growth, thereby reducing native biodiversity. As an annual, Himalayan balsam dies back in the winter, and where the plant grows near water it can cause flooding and erosion.
Like most introduced plant species Himalayan balsam arrived in the UK without any of the natural enemies that keep the plant in check in its native range. Without these natural enemies, Himalayan balsam is able to grow faster and has a greater ability to reproduce, giving it an advantage over native species. Traditional control methods are currently inadequate in controlling Himalayan balsam in the UK. This is often because the plant grows in inaccessible areas or sites of high conservation status where chemical control is not an option.
A single plant can produce up to 800 seeds in autumn which it ‘fires’ up to 7 metres away and seed can even survive in water for up to 18 months. Unbelievably for a plant related to the Busy Lizzie, this invasive plant can grow up to 3 metres tall and is a real thug, crowding out adjacent plants.
Last year, I noticed some plants on nearby waste ground which is at least 200 metres from home but this morning I found one in my flower border! It is only about 1 metre high but in full flower so I am about to remove all traces of it before it has a chance to set seed! Pity it is such a thug, it is quite pretty! The hooded flowers remind me of an ancient military helmet and it is one plant that would be guaranteed to grow in the most difficult areas of the garden!