Weedkillers – beyond glyphosate-based herbicides

First published by Rattan Direct on 1 July 2016.

Despite our fine words about weeds and wild flowers, there are some plants that are downright annoying. Couch grass and other grasses are my personal bugbears at the moment: on the path and in the flower bed, between the vegetables, creeping along through the fruit. I’m not over the moon about dandelions either. And I’m starting to feel a bit cross in the direction of the Welsh poppy.

Welsh Poppies, Baltasound, Shetland. A garden plant which freely naturalises. Glyphosate
Welsh Poppies, Baltasound, Shetland. A garden plant which freely naturalises. ©Mike Pennington and licensed for re-use under Attribution-ShareAlike 2.0 Generic Creative Commons licence.

We all have our own (un)favourite plants that can turn into out-and-out enemies if we’re not careful. You may recognise one or two of yours in rogues’ galleries like this one from the Royal Horticultural Society.

But we don’t want stress levels rising when we’re relaxing at the garden table or on the sun lounger. Are herbicides the answer?

Let’s just use the spray!

Hang on a moment! Herbicides or weedkillers are extremely strong substances. Yes, they kill unwanted plants but they can also damage the very garden plants you love and want to keep. And they can damage and be extremely dangerous to humans and animals.

There’s been increasing concern about the chemical glyphosate in recent months as the World Health Organization and the European Parliament have been investigating how long it hangs around, its unwanted presence in food and its potential to cause cancer and adversely affect the liver and kidneys.

Glyphosate (also known as glycophosphate) is the most widely used herbicide in the world and is very good at eradicating deep-rooted perennial weeds. You might know it as Roundup or Tumbleweed. The danger to humans may mean the withdrawal of glyphosate-based weedkillers from home gardeners in the UK, and being banned from use in public open spaces. A final decision will be taken this summer.

Herbicides at a garden centre. Glyphosate
Herbicides at a garden centre. Sarah Buchanan

If glyphosate is out, what are the alternatives?

  • Hot water is useful for spot treatment (watch out for neighbouring plants, of course). Australian research shows that it’s as effective at weed control as glyphosate.
  • Sprays based on acetic acid (much stronger than the vinegar you and I put on fish and chips). These weedkillers are non-selective and biodegradable. Weedol Fast Acting Weedkiller and Headland New-Way Weed Spray contain acetic acid.
  • Sprays containing pelargonic acid, a substance that occurs naturally in pelargoniums, apples and grapes. It’s non-toxic and breaks down readily in the soil. Neudorff Superfast & Long Lasting Weedkiller contains pelargonic acid.
  • Herbicides using fatty acids which disrupt the plant’s cellular structure, causing them to become dehydrated and die. It’s good at eradicating annual weeds and can be used around vegetables. Bayer’s Natria Super Fast Weedkiller contains fatty acids.

If you’re going to use a herbicide, now is the time to do it. In mid to late summer weeds have a large surface area to take it in. Choose your poison, read and follow the directions on the label, and take great care.

Other methods of weed control

Keep on top of weeds by hoeing and hand weeding. Don’t let them flower. Go for physical attrition: regular slashing of couch grass with a sharp knife, for example, weakens and loosens the plant in the soil. Use a flame gun on paving slabs and driveways when the foliage is dry and make sure you allow sufficient burn-time to kill deep-rooted weeds, such as dandelions.

Dandelions grow anywhere. Glyphosate
Dandelions grow anywhere © Christine Westerback and licensed for reuse under Creative Commons Attribution-ShareAlike 2.0 Generic licence.

Use barriers such as mulch or edging.

Use weed-suppressant fabrics over recently cleared soil to prevent the old weeds from growing again and new weeds from becoming established.

Lather, rinse and repeat

Unfortunately, this isn’t a one-off job. A range of approaches works best but whatever you decide to do, you’ll have to do it time and again.





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