The Organic Gardener’s Guide to Weeding

With a combination of natural methods, organic gardeners can keep their gardens as weed-free as their synthetic herbicide-spraying counterparts.

Pull weeds sooner rather than later—they have a weaker root system when they're small. Uryupina Nadezhda/Shutterstock

Weeds do more than make a garden look unsightly; they compete for the critical resources of water, nutrients, and space. They can also potentially stunt plant growth, or even strangle vulnerable plants at the seedling stage, as well as significantly reduce the ultimate fruit and vegetable production of a garden.

Sadly, there’s not one fix-all method of managing weeds for organic gardeners, but on the upside, all the following methods are much more user-friendly than dealing with toxic chemicals such as glyphosate (a widely used chemical found in Roundup and other popular herbicides).

In most cases, several methods used together will achieve the best results. It all starts with preventing weeds from emerging in the first place, whenever possible.

Weed fabric is a popular way to manage weeds in larger areas. Attasit saentep/Shutterstock

Before They Sprout

Mulch is one of an organic gardener’s best allies in the war on weeds. Wheat straw, pine straw, grass clippings, and shredded leaves are just a few of the organic materials that can be applied in preparation for a spring/fall crop, to overwinter the garden, or to keep down weeds between plants during the active growing season.

Ideally, these mulches should be applied at a depth of two to three inches to sufficiently smother weed seeds. Keep it away from the stems of any growing plants. Be sure to know the source of the mulch, particularly wheat straw, since foreign weed seeds could be accidentally introduced to the garden.

Lay newspaper and plain cardboard (the shiny, printed stuff may contain chemicals) over the garden between plantings, or repress weeds on paths between garden rows and beds. They make highly effective weed-smothering mulch—both before seeds sprout and while they’re still at the seedling stage. Since weeds are energetic, put down several layers.

Wood chips that haven’t been aged for six months are best kept for ornamental use, and not added to vegetable beds because they can rob the soil of nitrogen as they break down.

Weed-Free Zones

Have you ever been to a local nursery and noticed the high-tech fabric held in place with landscape nails covering the bare soil under your feet? There are several types of weed blocks available, from solid, impermeable plastic materials to those made of a mesh that allows moisture and fertilizer to seep through.

While a home gardener can use the impermeable type, it requires drip irrigation installed underneath, so let’s focus on the permeable mesh, which can be used with overhead or drip irrigation. Some come with holes in them for vegetable placement, but more common are large rolls that can be either laid between planting rows or laid out over the entire garden, with holes manually cut by the gardener for the individual plants.

Weed block can also be used in raised beds. While better products are designed to last several seasons, folding it up and storing it out of sunlight when not in use will make it last significantly longer. Instead, cover the beds with mulch, which will break down over the non-growing season and add nutrients to the soil.

Wheat straw, pine straw, grass clippings, and shredded leaves can be used as mulch. Jon Rehg/Shutterstock

Here Comes the Sun

When an area is filled with weed seeds or already taken over with active weed seedlings, solarization may be the best option. This means keeping a particular section of the garden or a garden bed out of production for a month or two.

Start by turning the top few inches of soil with a till or spade. Water thoroughly to a depth of three or four inches, and then cover it with a double layer of clear painter’s plastic, stapling or nailing down the edges to keep the heat inside. Resist the temptation to use black plastic, because, surprisingly, it does not get as hot as clear.

Do not till the soil after the solarization period is complete, as this could bring up weed seeds from below that were not solarized. Mulch or use weed block between new plants to keep future weeds down.

‘Organic’ Chemicals

When it comes to eliminating weeds in the garden in a comprehensive, timely, and efficient manner, particularly on a large scale, sometimes there is no choice but to use a weed-control product. This has led to the “organic” herbicide market.

Yes, some purists will say that a chemical is a chemical, but organic alternatives are typically made from naturally derived oils (such as clove oil, eugenol extracted from cinnamon, clove, bay leaves, and citrus-based d-limonene), acids (particularly citric and acetic acid, such as that found in 20 percent horticultural vinegar), and iron compounds (aka chelates).

They are most effective on seedlings and weeds that don’t grow overly large, because they are “burn-down” herbicides that damage a plant’s leaf structure and cause its quick demise. Unlike their synthetic counterparts, they are not systemic—meaning that they do not “go down to the roots” and are therefore less effective on plants with large root systems, rhizomes, tubers, or bulbs, as well as perennial broadleaf and grassy weeds (unless caught very young).

Some judicious hand-weeding and applying boiling water or regular-strength white vinegar complement these methods for a truly comprehensive approach. There are several handy tips on all three in the sidebar.

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Keep It Green

One of the most effective ways to remove weeds is by using a handheld propane-fueled weed torch, as it leaves no toxic residue. But if you’re looking for a cost-effective solution with items you already have at home, here are some options:

Hand-Weeding

Don’t wait! Smaller weeds have a weaker root system. Work when wet, when the roots are looser. No rain? No problem—hose down the area first. Always grab weeds at their base to get the best leverage and avoid ripping off only the top growth. Shake them to return soil still attached to their roots to the garden.

Valuable Vinegar

While horticultural vinegars have an aggressive 20 percent concentration, even common household vinegar can be highly effective on weeds. Spray it on full strength, or add a cup of salt and two tablespoons of liquid dish soap (organic preferred) to make a robust solution. Repeat, if needed, in three to five days.

Heat Things Up

Boiling water is easy and cheap and works well on weeds with no other plants nearby. A tea kettle makes a good applicator. Be sure to handle carefully to avoid dangerous splash back. Re-treat in five to seven days, if needed.