Finally got got off the waiting list and been offered an allotment plot. It's been empty for a while and is completely covered in horsetail. I've just been reading that Horsetail is the 'lodger from Hell' and the best I can hope for is a continual fight. Any suggestions how to start? Is it worth covering and mulching while I work on a small area at a time? Should I just spent a few months weeding and not worry about planting till next year? Any help would be appreciated, thanks.
If you are willing to put in the time weeding, just go ahead and plant - might as well get something useful grown while you are weeding. Horsetail is a pain to get rid of but really easy to spot, and it does not tend to shade out your actual crop plants - just keep pulling it whenever you spot it.
You could try the usual methods (smother crops, solarizing, etc) but horsetail and cockroaches will be the flora and fauna that are still here after armageddon, IME, thus my suggestion to get on with growing something useful. Of the nasty persistent weeds I have to put up with, it's the least offensive in many ways (I'll trade you ALL my creeping buttercup for horsetail.)
I tried various ways to control this weed including herbicides, vinegar, boiling water and propane torch. This weed can spread underneath a flagstone that is two feet wide and pop up on the other side.
The most effective method is to manually pick the tails after they have grown a few inches tall or more. If you keep doing this year after year they will loose vigor.
Another effective method is to put a barrier in the soil around your plot. I like EPDM food grade pond liner. You can dig a trench six or eight inches deep, place the liner inside and backfill with soil. Follow up with hand picking and you should see results in a few years.
This plant is hard to remove, because its roots may be meters deep in the ground, and it is resistant to many herbicides. It's also one of the first plants to emerge after a volcano eruption and one of the last to die in polluted areas.
However, it need soil with plenty of silicium (sandy or clay), it doesn't like shade, and it grows best on poor, bare soil. So the best way to surpress it is probably to alter the soil by applying plenty of fertilizers and grow other vegetation that overshadows it. However, I don't think you will get rid of it very easily. After all, the plant has deep roots, and a thin top layer of well fertilized humus won't stop it.
I have used RoundUp on horsetail and it worked to a large extent, but…
The Horsetail needed to be damaged with a soft broom first, as otherwise the herbicides just runs off it.
You will not get all of it the first time, so repeat every few weeks.
Then you just need to pull up by hand EVERY bit that comes up, every few days and it will get defeated.
Weed killer meant for Poison Oak works better as it is designed to break through the waxy barrier Horsetail uses to protect itself. But it just kills the visible portion. It grows back. I am redoing my rock garden with a wide section of pond liner so I at least have some areas free of this menace from prehistoric times. I'll use rubber mulch from Home Depot to give an appearance of formality. Hoping the Horsetail doesn't pierce the liner. It grew right through my kids vinyl pool liner.