Homemade Weed Killers That Really Work

And Other Smart Ways to Suppress Weeds

Two dandelions on meadow grassland.
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Few things give a landscape a more untended look than masses of weeds. One way to deal with pesky weeds is to kill them with store-bought, chemical herbicides. But this approach doesn't cut it with gardeners striving for landscapes that are not only weed-free, but also safe for people, pets, and wildlife. For them, mere weed control isn't as important as achieving weed control without chemicals. In fact, such gardeners sometimes choose to tolerate weeds such as wild violets, rather than fighting them.

However, if you're the type of gardener who's "green" but who loves well-manicured landscapes and perfect lawns, too, you must look for smart ways to control weeds. Luckily, there are some homemade weed killers you can use. They are safe, and they really work. Moreover, you can supplement them with other strategies that are effective against weeds, yet won't harm the environment.

Homemade weed killers generally work best around a garden (for example, the area along a garden fence, where weeds sprout up) rather than on lawns because they kill whatever they come into contact with (such weed killers are said to be "non-selective"). So if you spray them on a lawn weed, and if some of the spray misses the weed and gets onto your grass, the grass will die.

Vinegar

Vinegar spray is one of the best homemade weed killers. It's easy to prepare and effective against a variety of weeds. All you need for ingredients are:

  • A vinegar that is high in acetic acid
  • A surfactant (this substance doesn't kill weeds; its role is to help the vinegar herbicide penetrate into the weeds' leaves)

Pour the ingredients into a spray bottle and shake to mix.

Apply when the weather report says you'll be getting a few continuous days of sunshine. Rain would wash the vinegar off the weeds too soon and most of the damage happens when the sun hits the weeds' leaves.

Spray directly onto the weeds, being careful to keep it away from other plants.

Rubbing Alcohol Solution

This astringent substance works by removing moisture from the weed's foliage. Deprived of its life force, the weed dies. Mix the solution in a spray bottle for ease of use.

Preparation is as simple as diluting the rubbing alcohol with water: use a quart of water to dilute every two tablespoons of rubbing alcohol.

As with vinegar, apply on a sunny day, and spray directly onto the weeds, being careful to keep it away from other plants.

Boiling Water

This homemade weed killer is the easiest of all to prepare and use. You won't be doing any mixing at all, and you can apply it at absolutely any time you wish: day or night, with or without sunshine, even in the pouring rain.

Simply boil some water and pour it on the leaves of the targeted weed. Pour enough so that it seeps down into the roots, too. It's helpful to have a kettle to boil the water in, so that, when you pour, the stream of boiling water can be directed with a spout. But where precision isn't necessary, even a pot serves the purpose. Sometimes, though, your pouring must be precise, as when you're killing a weed that's growing right near a good plant: Scalding the good plant with the boiling water could harm it.

Corn Gluten

Corn gluten falls into a different category. It's a weed suppressor rather than a weed killer, making it impossible for weeds to appear in the first place. Corn gluten is most commonly used to control crabgrass (Digitaria).

Corn gluten, if used properly, inhibits the formation of those first roots crabgrass seeds put out after they germinate. But proper use requires two things:

  • Application must be timed so as to coincide with crabgrass germination, which happens when the lilacs (Syringa vulgaris) in your region are blooming.
  • Application must also be timed so as to occur during a dry period.

Here's how application works:

  • Corn gluten is organic, being a powder that's left over after corn is milled. There's no mixing: You simply spread the powder over the soil.
  • Water the corn gluten into the soil after application (about 1/4 inch of water is required).
  • But after you water it in, the weather must be dry for a couple of days. Otherwise, the roots won't be killed.

The drawback in using corn gluten is that there's an element of luck involved. If it rains during the whole week when crabgrass is germinating in your area, you're out of luck.

As with homemade weed killers proper, corn gluten is non-selective: It suppresses all types of germinating plants, not just weeds. So it's not something you'd want to put down on your grass at a time when you're overseeding your lawn.

Other Smart Ways to Suppress Weeds

While vinegar, rubbing alcohol, and boiling water really do work to kill annual weeds, they won't work against some of the tougher, perennial weeds. For such weeds, you'll have to take different measures. You can still stay organic, but it takes some extra creativity and work on your part.

For example, if you're persistent, you can control Japanese knotweed (Polygonum cuspidatum) without resorting to the use of glyphosate herbicide. Cut the knotweed down, clear dead canes away, and place tarps over the ground. Deprived of sunlight, the weed's food reserves will eventually be exhausted. But not before it sends out shoots beyond the tarps' perimeter in search of the needed sunlight (you'll be removing these shoots for years before exhaustion finally sets in).

Similarly, covering ground in the garden with any of the following helps to suppress weeds:

Even something as simple as crowding out weeds is an effective tactic. That's why some people don't need mulch for their cottage gardens: The plants are packed so closely together that there's no room for weeds. Likewise, a healthy lawn will grow so thickly that weeds won't have any openings to exploit.