Let's face it, weeds are part of every gardener's life. The dreaded plants complete with our gardens for nutrients in the soil, they hog the sunlight, and they limit growth potential for our veggies. That's why controlling weeds is an integral part of every gardener's master plan. While you might be tempted to pull out an industrial-sized jug of a commercial killer, there are better ways to tackle weeds.
Natural weed killer is a cinch to make at home and can be much more affordable than the stuff they sell at the store. It is also better for the overall health of your garden and the environment – not to mention your own health.
We've tested a variety of natural weed killer recipes that you can use to control weeds naturally, and we'll show you what worked best in our gardens.
Why Use Sustainable Options?
True – there are a lot of commercial weed killers and herbicides on the market. Go to any big box store, and there are aisles full of them.
Commercial weed killers are effective because they contain harsh chemicals that kill weeds immediately. Incidentally, some of those harsh chemicals can also kill your vegetables and any other plants in the area if they get spray on them.
The other downside is that compounds such as 2,4D (dichlorophenoxyacetic acid) and Roundup (glyphosate) can bind themselves in the earth or get washed into wells and waterways. These chemicals can be toxic to the good microbes and life in your soil – such as earthworms – as well as the fish in nearby waterways.
Chemicals in commercial herbicides have also been linked to human cancers. For instance, glyphosate is now listed by the World Health Organization’s International Agency for Research on Cancer (IARC) as a probable carcinogenic. Not something you want around your food.
Then there's the fact that commercial weed killers aren't cheap. It's hard to see why they are worth the trouble when you can make your own natural weed killer at home for a fraction of the cost.
Natural Weed Killer Recipes
Homemade killers can help to rid your garden of weeds without endangering the health of your garden. The best part is that you can make them inexpensively from everyday items, like vinegar and dish soap.
Vinegar, Salt and Dish Soap
A mixture of vinegar, salt, and dish soap is an excellent alternative to harsher chemicals and works exceptionally well. It's one of the most popular recipes out there for natural weed killers.
Vinegar contains acetic acid which dries up the cells in the plants. Salt is also a good natural dehydrator, and it also inhibits plant roots from taking up water and nutrients. Dish soap is a surfactant and helps keep the vinegar and salt stuck to the weed instead of running off on to your garden soil. Combined, it makes an effective weed killer.
To make, combine:
- One gallon white vinegar
- One-half cup salt
- One tablespoon liquid dish soap
Spray this solution liberally on the plant. It may take a day or two to see results, but soon you will have a dry, brown, dead weed.
It's best to spray your concoction onto weeds on a warm sunny day. That way the sun will work with the spray to dry up and kill plants. This mix works best on annual weeds. Perennial weeds which have longer root systems will grow back and need multiple treatments.
Combine spraying with hand weeding to get at those stubborn perennial weeds. You can pull the weed, exposing the roots and spray right down into the ground to saturate the roots.
Boiling Water and Salt
Do you have weeds in the cracks of your walkways or in the paths between rows? Boiling water is an effective natural weed killer and works well in places where weeds pop up but are not close to your garden plants. Amp up its effectiveness with some salt.
- Boil a pot of water
- Add 2 tablespoons of salt
- Pour on the weeds.
Keep in mind that the salt is not the best thing to add in garden beds because it can kill good plants as well. It's excellent in areas where you want to clear out plant life or kill plants in the cracks in cement. Be sure to pour the boiling water slowly to avoid backsplash. I use a tea kettle since the spout helps me control the water flow.
Lemon Juice, Vinegar and Rubbing Alcohol
Lemon juice is an acid that will dry up the weeds. If you live in a warmer area and have a lemon tree, then this is an economical option for you. Otherwise, you can purchase fresh lemons or lemon concentrate in a grocery store.
Along the same lines as vinegar and lemon juice, rubbing alcohol can be an affordable natural weed killer. You can also use a gallon of cheap vodka. It works in the same manner by drying the weed up and killing it.
To make, combine:
- 3 tablespoons of isopropyl alcohol
- 1 quart of water
- 1 half quart vinegar.
This works best on young weeds. Older, tougher weeds will need several treatments.
Borax and Dishwashing Detergent
If you keep borax around the house for cleaning, then you already have a powerful weed killer right at your fingertips. Adding a little dish soap helps break down the weed's protective barrier and helps the mixture stick to the plant. Like other mixtures, avoid getting this on the plants you want to keep alive.
To make, combine:
- 1 tablespoon of borax
- 1 tablespoon of dishwashing detergent
- 1 liter of water
This method may seem a little unusual, but trust me, it works. Combining red pepper hot sauce and vinegar to boiling water and you have a potent mix that will destroy anything it touches. I like to use this mix when I have things around the house I want to use up, like pickle juice or pepper juice.
It's likely the action of the vinegar and the boiling water that does most of the damage, but I discovered, after dumping an empty pot of crab boil water, that the hot sauce seems to add an extra punch to weeds.
It's also an effective pest control. You can substitute cold water and spray the mixture on plants to keep the bugs away.
To make, combine:
- A 12-ounce jar of hot sauce
- 2 cups of vinegar
- 2 gallons of water.
Apply while the water is still hot to the plants you want to kill.
Pine-Sol and Dishwashing Detergent
I love the smell of this weed killer, and it is relatively inexpensive to make. This recipe has the added benefit of keeping ants and other small insects at bay.
To make, combine:
- 1 part dish detergent
- 1 part Pine-Sol
Other Natural Weed Killers
While these natural weed killer recipes will help eradicate weeds in the garden, any good weed control routine requires a few different lines of attack. To make sure you are eliminating bad plants, combine your liquid killer with the following natural strategies and you'll be weed free in no time.
Hand weeding may be the least popular method of ridding your garden of weeds. However, it is still one of the most highly effective. There is an old Chinese garden adage that says the best weed control is the gardener's shadow.
Hand weeding is great for perennial weeds which need some digging action like dandelions. Using a weed tool or a large screwdriver can help you get down in the soil after those tap roots.
An excellent and often overlooked natural weed killer is your lawn mower.
Annual weeds grow in the spring and summer and are killed by frost in the fall. They produce seeds which will overwinter in your garden and grow again next year.
One of the best ways to control annual weeds is to kill them before they go to seed. Mowing is a good way to cut off the flowering heads before they can send seeds out into your garden.
Mowing does not necessarily kill the growing weeds. However, it does stunt their growth and stops them from making seeds temporarily at least. If you keep at it, eventually you can eliminate some types of weeds because they won't get the chance to reproduce.
Mowing also helps curtail perennial weeds. Think of those “pretty” dandelion flowers all over your yard and garden. Dandelions can produce over 2000 seeds per growing season, and the seeds can live for many years in the soil. If you cut them down before they can seed, you can eradicate them over time.
Mowing is best for areas where plants won't be harmed by a regular trim, like grass.
Mulching attacks weeds in two ways: it prevents new ones from taking hold, and it smothers existing weeds. Lay down a six-inch layer of mulch where you want to control them.
Different types of mulch work better than others for controlling weeds. Try mint compost, also known as mint hay. The oils in the mint plants discourage some plants, with the added bonus of repelling some pests.
Cocoa shells are one of the best mulch options to control weeds but don't use it if you have pets, because they can be toxic to dogs.
Mulch is ideal as weed control in vegetable gardens or larger crops.
Common distilled white vinegar is useful in the spring if you are hoping to kill newly-growing weeds. It isn't as effective on tough, older plants, however.
If you want something stronger, you can purchase a garden-specific vinegar. Vinegar in the grocery store contains 5% acetic acid, but the more concentrated stuff has a whopping 24%. Keep in mind that vinegar at this concentration is caustic. It can burn eyes and cause skin damage. Wear gloves, protective clothing, and goggles when spraying.
Concentrated vinegar will also kill any good bacteria, insects or other small critters in your soil, so be careful where you use it.
Corn Gluten Meal
Corn Gluten Meal (CGM) is a natural weed deterrent. Iowa State University has been doing extensive research on using it to deter weeds.
It works by killing the seeds, not the plants. They have found it works particularly well on crabgrass, pigweed, and purslane. It works best if you pull the weeds first and then sprinkle CGM on the ground to prevent new seeds from starting.
You can buy CGM in powdered and granule mixes. The granule is easier to spread in your garden. It is most effective when spread in early spring before weeds emerge.
The university recommends spreading 20 pounds per 1,000 square feet and water it lightly into the soil. As a bonus corn gluten meal is 10% nitrogen and works as a side dressing fertilizer for vegetable plants.
This is a more expensive natural weed killer than some of the other options, but it shows promise as a useful tool in the garden.
A Note About Commercial Natural Weed Killer
There are a lot of commercial weed killers on the market. Many are natural products or want you to believe they are natural products. Take the time to read the labels. Organic herbicides will not contain chemicals or harmful fossil fuel products.
The word natural is not regulated, and companies often mark their products safe and natural when they are not. One way to evaluate a product is to look for the abbreviation OMRI. The Organic Materials Review Institute (OMRI) examines products to ensure that they meet organic and sustainable standards,
Buying from sustainable companies such as Peaceful Valley and Fedco can also give you peace of mind that you are getting a good product. Walmart and Home Depot are also carrying more organic herbicides, so keep an eye out.
Whenever you use something to kill plants – natural or not – use caution. Acetic acid, lemon juice, boiling water and rubbing alcohol don't know the difference between a vegetable and a weed. So make sure you aim your sprayer directly at the weed and use the stream setting so as not to hit a nearby lettuce plant.
Another trick is to use a cone or funnel to help aim your solution. Simply cover the weed and spray right down into the cone so to protect surrounding plants.
Regular grocery store vinegar will not harm your garden soil. However, stronger strengths of 24% acetic acid or more can lower your pH value temporarily. It may also temporarily disrupt microbes in the earth.
Use caution when adding salt. Salt can build up in the soil and become harmful. Soils with high salinity inhibit growth and prevent nutrients from going up into the roots.
Keeping on top of weeds does take effort, but you don't have to resort to harsh chemicals. Finding the right combination natural weed killers will make your job easier, and your garden – and the planet – will thank you.