This is a very good article, our expert Charlotte wrote about horsetail and what we did (and you can do) to get rid of it the organic way. Horsetail likes damp conditions. The City Council put in some drainage for us, which will hopefully help. Other things to do are:
- Lime the soil to raise the pH a bit. Horsetail does better in lower pH soils which Empty Common Community Garden (ECCG) has.
- DO NOT attempt to dig out the horsetail roots just take the top off and drown. The roots are super long, spreading wide and deep. They also have nodes on their roots that are activated to produce lots of root growth when a root is broken.
- Take off the sporing heads as they emerge in spring. Drown these in water for at least three weeks before putting the sludge on to a piece of waste land. DO NOT add them to the compost just in case the spores are still alive. The sporing heads are small so not a lot of organic matter is lost.
- Mulch the land with cardboard and then woodchips or council green waste compost and when the horsetail emerges, hoe it. Just mulching doesn’t work, in fact it makes the problem worse because horsetail likes the damp conditions created by mulching, it grows straight through the cardboard and finds there is no competition so takes off. Horsetail isn’t good at competing with tall plants.
- The hoed plants should be drowned in the wheelie bins for at least three weeks. The drowning water should be returned to the beds BUT NOT when there are vegetables growing as it is very smelly, microbe-rich stuff.
- The sludge should be added to the compost along with any drowning water - if the compost needs moistening. The reason for returning everything is to return the nutrients that the horsetail has accumulated back to the soil for other plants. Often some plants compete better than others because they are good at accumulating minerals that others aren’t. Horsetail is a good mineral accumulator, it accumulates silica from deep down and competes well against other plants in low silica soils. Adding the drowning products back to the surface makes the silica and other nutrients available to other plants improving their competitive ability.
- In summer possibly try planting lots of marigolds. They are said to be good at deterring horsetail. Also try growing a tall crop. A must-see video of horsetail spores is here. It makes it seem tragic to drown them. This plant is a living fossil and there used to be forests of it growing 100ft tall... so things could be worse.