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Horsetail – more or less

May 20, 2013 Gotalottie 1 Comment

We receive quite a few emails asking for information about Horsetail (Equisitum Arvense). Inaccurately called ‘Mares Tail’ by many people on allotment sites; it’s a stubborn weed and virtually impossible to eradicate.

Here’s a photo from our plot (to the left) and the empty plot next door (to the right). It would be a brave person to take that on.

it’s pretty daunting seeing this next door

We’ve just received an email from Hayley:

‘Hello.  Just read your article about horsetail.  We bought our house in September and the borders in the back garden were very overgrown …. no sign of HT.  So a couple of weeks ago when the weather started to improve, my husband and I dug over the borders, feeing them up of grape hyacinth and grass and planted some nice new bulbs and flowers.  We now have Horsetail growing around our rose tree (already established) and amongst all our other flowers.  Any suggestions?’

Our reply:

‘Hi, thanks for your enquiry about this nasty little weed.

The reason that you didn’t spot this in September is that it was probably in decline by that time of year and other weeds had moved in to fill the space.

In March it would have probably thrown up some brown spears a bit like asparagus and these would attempt to send spores all over the garden. Always best to delete these with a knife and dispose of in the rubbish.

April/May – it comes with a vengeance and this is what you are seeing. It reaches full growth by July and a height of 40cms.


Assuming that you’ve cultivated the soil already to remove all other weeds, etc. Don’t cultivate any more this year. If you haven’t cultivated – then don’t.

Forget weedkillers, covering with plastic, etc – nothing will kill it. Weedkillers ‘may’ kill off some top growth but it will come back harder next year and you will feel like moving house. You can’t kill it but what you can do is to convince it to go next door.

When light brown spears show – leave them until they’re minimum 7cms tall and try to ease them out with as much root as possible, certainly before they get to 10cms tall. The trick is to let them use as much energy as possible getting to the point where they’re about to photosynthesise and then delete them. This will serious weaken the rhizome underneath. The trouble is when a shoot is pulled it triggers another rhizome to make another shoot, but it does inhibit it a little. 

Meanwhile and you should do this as soon as possible – buy some agricultural lime and start to sweeten the soil. The HT is there because the soil is alkaline probably 6.3 or less and you need to gently get it back to about 6.8 and that will take 3 years. The HT will start to move on at 6.5+.

First liming is now at 300-350gms per sq metre. Work this into the soil a few cms and water in. Don’t use any more this summer else you’ll kill your other plants. Add a mulch of grass clippings this summer (5-7cms). In October add another 400gms per sq metre and work in a little deeper. No fertiliser this year else that will lower the pH again. Plant lots of French marigolds this year if you can. Also increase your planting if possible to reduce the amount of light getting to the shoots – make them work harder to get to the light, all of this weakens the rhizomes.

Fertilise in early spring with Fish Blood Bone and a month later add another 200gms per sq metre of lime. More grass clippings as mulch in the summer. In the October - lime as before. Fertilise in early spring. Etc..

Keep pulling the HT shoots as above, but don’t pull them when they’re too small, it’s better to be patient and leave them to grow to 10cms.

It will eventually go completely but remains of the roots will be there still 50cms down. If you add small amount of lime each October (50-100gms per sq metre) the soil will stay sweet and the HT won’t ever show again. Mulch with grass clippings every summer.

Don’t forget the beds in the front of the house, else it will possibly move there instead. ’

We’re not Horsetail free yet, but it’s improving.

Currently there is "1 comment" on this Article:

  1. Kay Sexton says:

    Good tips. We don’t have a problem with horsetail on our site, thankfully, but I do know one site that’s completely infested with it, I shall point the allotment holders there in your direction for some help!

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