The future of natural weed killers

Cathy Thompson on working without Roundup, plus a recipe for courgette gluts

24 July 2019
By Cathy Thompson

I do not use many chemicals in the garden: my working life has taught me that mostly they are just products with the potential to alarm the home gardener into believing they are essential, thus lining the pockets of big business.

However, the weed killer glyphosate (the active ingredient of Roundup) is one that I am going to find hard to let go of. When the WHO declared it potentially carcinogenic in 2015, they added it to the category that also includes red meat. Interesting – and the ban on red meat will come into effect when? But developments in the USA and Europe mean that, like it or not, glyphosate is going to leave our gardening arsenal.

I would never use glyphosate on a large scale, because I am not a farmer in need of efficient and cost-effective weed control. If I am preparing a new border on grass, I always lay landscaping fabric or old carpet (if I can get hold of it).

Cardboard topped with a mulch of pulled weeds or other dead organic matter works too. Lift the smothering layer off six months to a year later and the ground will be as clean as you can get it.

The situations in which I am going to miss glyphosate? I use it to:

  1. spot-treat bindweed in borders;
  2. control weeds on my many garden steps;
  3. control the spread of vicious little Muehlenbeckia complexa that I stupidly planted near a 500-year-old tower wall

Now the Muehlenbeckia seedlings threaten every nook and cranny of the old stone and I have to act fast! I think I will be trying one of the new generation electric désherbeurs (weeders).

The plant cells explode as a result of heat shock when spot-treated; there is no question of burning and no danger to surrounding plants. Admittedly, something as tough as the Muehlenbeckia will need up to three treatments, but that was standard with glyphosate too.

For paving and steps, I will go back to my old ways. Boiling water (particularly with a spoonful of salt added) is ideal: again, this is a thermal shock treatment. Rock salt works reasonably well too, when scattered on paths and edges. A spray of horticultural vinegar (containing up to 20% acetic acid), mixed with a little washing-up liquid (to help it ‘stick’) also does the trick.

The spot treatment in a border is the trickiest to handle. It is almost impossible to be completely rid of bindweed in an existing border, although repeatedly pulling the tops off emerging shoots does weaken it.

In the past I have been down on my hands and knees with a jam jar full of glyphosate, a paint brush and rubber gloves. You simply hold the bindweed leaves (or dock, etc.) in your rubber-gloved hands and paint on.

But you have to be cautious: bitter experience has taught that if something like a hosta gets even a whiff of chemical, it will turn toes. In this situation, I will be joyfully continuing with the jam jar method, but exploring the power of horticultural vinegar and organic weed killers, made from naturally occurring nonanoic plant acids.

From potager to kitchen

We are nearly into glut season again! Last year some of you sent me wonderful recipes for dealing with excess haricots, courgettes and tomatoes. This month and next I am sharing a few reader ideas with you. For August, the spotlight is on Di Murrell’s sweet and sour courgette pickle recipe.

You need: 2kg courgettes (sliced to 5mm thickness); 60gm sea salt; 170g onions, cut into fine rounds; 600ml white wine vinegar; 600ml water; 300g sugar; 4tsp curry powder; 1tsp ground black pepper.

Plan four days for this project! On Day 1, mix the sliced courgettes with the salt and onions, leaving them in a covered plastic or earthenware bowl.

On Day 2, rinse the mixture under running water and return to the bowl, then add the water, vinegar, sugar, curry powder and pepper. Mix well and, as Di says: ‘leave them to get to know each other’. Cover with a cloth.

On Day 3, strain off the liquid, heat it to boiling, then pour it back over the courgettes and onions.

On Day 4, bring the courgettes and onions in their juice back to the boil and cook for three to four minutes, then pour into sterilised jars. Enjoy with cheese, charcuterie, or a raclette supper!

OVER TO YOU

What is your favourite non-chemical weed-killing method? Email Cathy at editorial@connexionfrance.com

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