How to kill weeds

A few pieces of wood and some builder's plastic will allow you to build an effective chemical free device to kill weeds naturally.

A few pieces of wood and some builder's plastic will allow you to build an effective chemical free device to kill weeds naturally.

Weeds are fine in the wild, but they are nasty little thieves in the garden, soaking up your time and nutrients your vegetables could use.

If your garden is just a couple of small beds, you can easily rake or hoe freshly sprouted weed seedlings and pull by hand if they get away from you for a few weeks. But as you scale up the size of the garden and the yard, more efficient strategies are required.

A workplace accident involving 2-4D, deisel fuel and my right eye put me off chemical herbicides for life.

Here are a few more benign strategies that I use, which require nothing stronger than water, salt and vinegar.

Sheet Solarization

Use the sun’s energy to force weed seeds to sprout or to kill a mass of established weeds. If you have a large area — such as a chunk of lawn you’d like to convert to garden — buy a roll of black plastic and stake it down over the entire area for about six weeks in sunny weather. Heat and water deprivation will kill everything underneath.

For established gardens, I use a simple wooden frame made of 1X2s with a sheet of clear builder’s plastic stapled on. Build the frame to the same outside dimensions as your garden beds and lay it over top of the soil for about a week. The trapped heat will sprout the weed seeds, which can be plucked from the soil, raked, hoed or torched.

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Propane Torch

Organic farmers use this technique to burn off weed seedlings between the time they plant their seeds and when those seeds are due to sprout. You can purchase home-sized torches — with names such as Weed Dragon and Giant Weed Torch — that attach to your barbeque propane bottle. I use the Weed Dragon in conjunction with the solarizing frame to burn off freshly sprouted weeds by the hundreds. All you have to do is pass the flame over the surface of the soil to steam and kill the seed leaves. No need to incinerate them. If they are steaming, they are dead.

Boiling water

Mature, established weeds with long roots will not immediately succumb to the torch, but a kettle of boiling water might do the trick. Boiling water is especially useful for killing weeds between patio stones, in cracks or on garden paths lined with wood chips that you don’t want exposed to flame. Pour the water slowly over the weed to allow the water to penetrate deeply enough to kill the roots. If you pour too fast, the water may damage nearby plants. This method also kills the naturally occurring beneficial organisms in the soil, so I tend not to use boiling water directly on my garden beds.

Salt and vinegar

A solution of salt, vinegar and dish soap is an effective non-selective weed killer, in fact it will damage any plant it touches. It is a chemical-like product, but one that is harmless to children and pets. Dissolve one cup of salt in one quart of ordinary vinegar, then add one tablespoon of dish soap (to help it stick) and pour into a spray bottle or a jar. Wet the leaves thoroughly on a dry, sunny day. Established weeds may take more than one application. The solution will kill the weed and any other plant it touches, so may want to use a brush to apply it only where you want it. If you pour the solution into the soil, nothing will grow there for a very long time, which might be useful on a gravel path.

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Send your gardening questions to rshore@vancouversun.com

• Randy Shore is the author of Grow What You Eat, Eat What You Grow, a guide to growing and eating sustainably all year round. Buy it online.

Want to learn more about natural weed killing?

Check out these Web sites chosen by us for more information on the subject.

The TipNut archive of tried-and-true homemade weed killer recipes is a great resource of information.

For some sobering reading on herbicides in groundwater, see the U.S. Geological Survey’s study of Midwestern aquifers.

Organic Gardening magazine has a cheery outlook on weeds and how to control them.

eco friendly weed killers

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