Natural and Organic Weed Control

In February 2014, the federal government agreed to review 23 active ingredients contained in up to 383 herbicide and pesticide products. Many of these chemicals have been linked to water contamination and cancer. Safe natural alternatives to dangerous chemicals for weed control are important for the environment and our health as well.

Eco-friendly options

The environmental groups Equiterre and the David Suzuki Foundation mounted a successful legal challenge leading to this future federal review. In the meantime, let’s consider our options for eco-friendly weed control.

Step 1: Mulching

The first step is to prepare or improve the soil our plants grow in. The addition of organic matter and the correction of drainage problems are initial steps in the right direction.

One of the best ways to control weeds in the garden is to apply a thick organic mulch layer, such as compost, well-rotted manure, shredded leaves, or straw. This layer blocks light from reaching weed seeds, so they can’t germinate and grow. Organic mulch also keeps your treasured plants healthy and strong and improves the soil, creating ideal conditions for earthworms and micro-organisms.

Step 2: Weed control

Vinegar or boiling water

White vinegar or boiling water can be sprayed or poured directly on weeds to kill them, but there is a danger that nearby plants can also be harmed if you’re not extremely careful. Too much vinegar in the soil can alter the soil composition and acidity plus negatively affect soil life such as earthworms. It is best to leave these weed control methods for weeds in sidewalk cracks, patios, and similar areas (see recipe on next page).

Weed killer plant

The Mexican marigold, Tagetes minuta, is known as the “weed killer plant” for its herbicidal root secretions that are toxic enough to kill many weeds, yet will not harm most other plants. A 2010 study found contradictory explanations for how this toxic substance is released, but it’s still a dream plant of sorts. The Mexican marigold destroys weeds, including bindweed, ground elder, ground ivy, and couch grass.

It also controls tiny worms called nematodes in the soil. Although the tall-growing Mexican marigold is not the prettiest of annual plants, it can be incorporated into a well-planned garden.

Note that sweet marigold, Tagetes lucida, is often mislabelled as Mexican marigold, so make sure you’re getting the right plant; ask for it by its Latin name.

Corn gluten meal

Corn gluten meal is an effective natural garden and lawn herbicide that also feeds the lawn. It controls weeds such as crabgrass, purslane, lamb’s quarters, many other weeds, and yes, dandelions as well. Corn gluten meal acts as a natural nontoxic pre-emergent weed control by inhibiting the germination of weed seeds by drying out the seed when it opens to sprout.

A byproduct of the corn milling process, it’s available in powder, granulated, or pelletized forms.

Powder can cake and is best applied with a hand seeder. Apply it directly on bare earth as it can’t work down through grass or mulch.

Granules can be applied using a spreader; pellets can be spread by hand. Both of these forms are far better and easier to apply.

Only buy organic corn gluten meal for best results and avoid substitutes. Apply as per product instructions. Usually this means two to three applications per year (early spring and early autumn). Corn gluten meal needs to be wetted with a fine mist after applying in order to work; then allow the treated area to dry out.

Newspaper for weed control?

Yes, newspapers can provide a very effective weed control method, especially for larger sections of the garden. Most newspapers today are printed with soy-based inks, making them much safer for the environment. Do not use glossy paper from magazines, pamphlets, and the like.

First, mow or cut back lawn or brush to ground level, leaving clippings in place. Next, cover the area with a layer of newspaper eight to 10 pages thick, making sure the newspapers overlap at the edges. It’s best to do this on a calm, nonwindy day. Then cover the whole area with about 1 ft (30 cm) of top quality weed-free soil, and you’re set to plant.

Controls for specific weeds

It may sound strange, but the best way to eliminate crabgrass and quackgrass from your lawn and garden is to ignore them. Ensure your lawn and garden are kept healthy by aerating, watering, mowing, and fertilizing properly.

Crabgrass

Aerating the soil and mowing your lawn at 3 in (7.5 cm) in height are effective means to control crabgrass. Combine these practices with increased organic matter in the soil and the periodic application of organic fertilizers for even more effective weed control.

Quackgrass

Never let quackgrass go to seed, even though it also spreads rampantly by rhizomes. Rhizomes are its thick, tough roots. New plants grow from nodes on the rhizome. Applying a thick layer of organic mulch is a great control method, as is the newspaper method.

Whatever method of weed control you use for your lawn and garden, choose a natural or organic one.

Dandelions, be gone!

As surprising as it may sound, you can rid your lawn of dandelions in one year, without any herbicidal chemicals at all. Sure, dandelions are pesky and persistent, but they are not indestructible. We can definitely be victorious in controlling, or better still, eradicating them.

Dig it?

Digging the roots out by hand is the absolute best way to get rid of dandelions. This may at first seem like a lot of crawling around on your hands and knees and an awful lot of digging, but think of all the healthy exercise you’ll get. Or if you prefer, there are long-handled weed pullers of all sorts to make the task much easier.

Time it right

It’s all a matter of timing. The best time to dig out dandelions is early in their blooming when the plants are at their weakest and the roots aren’t that strong yet. Dig out as much of the root as you can and dispose of it properly. Definitely do not allow dandelions to form their fluffy seed balls, for that’s when they proliferate the quickest.

For those with larger properties, consider using corn gluten meal to help control dandelions.

Pre-emergent: This type of herbicide inhibits a key enzyme that prevents the germination of weed seeds.

Avoid confusion

Corn gluten meal and corn meal are definitely not the same thing! Corn gluten meal is derived from the part of the kernel that is not used in corn meal. It isn’t really edible, but won’t hurt you. Corn meal that’s used in baking and cooking cannot suppress weeds.

Basic Weed Control Recipe

4 cups (1 L) vinegar
1/4 cup (60 mL) salt
2 Tbsp (30 mL) liquid dish soap

Mix ingredients together and pour into spray bottle. You can use boiling water instead of vinegar. Spray or pour directly on weeds. Make sure you only hit your target plants, the weeds! Apply only on clear, sunny days when no rain is forecast for a few days.