Horsetail on allotments: turn an invader to plant feed
Horsetail can be a real problem on an allotment plot but you can turn it to your advantage.
Horsetail is high in silica and a when soaked to make a tea which, is said, to coat the leaves of treated plants producing a fungicide and protect against blackspot, mildew and mint rust.
Depending on the quantity of horsetail available it can either be soaked in a lidded bucket of a water butt (This is useful if allotment site plot holders are prepared to spend a day on an allotment wide horsetail harvest).
The plants need to be fully submerged under the water so are best put in a sack or an old vegetable net pinned down with a large stone or to suspend it in a submerged weighted bag . Regular stirring is recommended. The fermentation process can range from 10 days to 3 weeks, depending on the ambient temperature. It can be left soaking longer to be certain that it is non-viable. During fermentation the mixture will produce gas which will bubble on the surface. Once the bubbling has stopped the it has finished bubbling the liquid can be strained and used. The are more details and photos at