5 Things You Should Never Use to Kill Weeds—and What You Should Try Instead

The battle against weeds is always a challenge. Some may not be too bothersome, but if left unchecked, they can deprive nearby plants of water and nutrients. Given how frustrating this can be, it's tempting to use any method necessary, regardless of the consequences. However, some of these can harm neighboring plants and reduce overall soil health.

Instead, consider other methods to keep weeds at bay. Ahead, experts share the methods to avoid and what to use instead to keep these pesky plants under control, while also protecting the health of your lawn and garden.

Gasoline

Gasoline is highly toxic and can contaminate soil and groundwater for prolonged periods. "[It] kills all plant life, including beneficial microbes in the soil, and its use poses a significant fire hazard," says Brandon T. Kail, founder of Rocky Mountain BioAg, a fertilizer and soil amendment supplier.

Instead: Use Boiling Water

For eliminating weeds in paved areas or cracks, Kail recommends using boiling water. “[This] kills the weeds on contact without leaving any harmful residues," he adds.

Boiling water is most effective on young, shallow-rooted weeds. Repeated treatments may be necessary for older, more deeply rooted weeds.

Horticultural Vinegar

Household vinegar is a natural and mild weed killer, but horticultural vinegar at a concentration of 10 to 20 percent is corrosive, and can kill desirable plants.

“It's non-selective and can harm beneficial insects and soil organisms,” he adds. Additionally, the vinegar's low pH can have a negative impact on soil health over time.

Instead: Mulch

A safer and more sustainable approach to suppressing weeds is to use a thick layer of mulch, such as wood chips, straw, or compost

"Mulch blocks sunlight, preventing weed seeds from germinating," says Kail. "It improves soil health as it decomposes.” Mulching also allows the soil to retain its moisture, so you won't have to water it as often.

Salt

Spreading salt can effectively kill weeds by drawing out moisture and dehydrating plants. However, salt can accumulate in the soil, making it difficult for other plants to thrive. "High salt content can destroy soil structure and persist for years, rendering the soil barren," says Kail.

Instead: Use a Flame Weeder

For small, persistent weeds, Kail recommends using a flame weeder. This device uses a burst of heat to rupture the plant’s cells, causing the weed to wilt and die. It's particularly effective for controlling weeds in pathways and driveways, as it does not introduce any chemicals, and causes no long-term damage to the soil.

However, Kail advises using flame weeders with caution; avoid using them near flammable materials.

Harmful Herbicides

Synthetic weed killers might promise instant results, but their impact on the environment can be very concerning. These substances not only endanger water systems and harm beneficial pollinators, but they can also negatively affect neighboring plants.

Plus, it's important to remember that weeds are persistent. They'll come back, and you'll quickly find yourself trapped in a cycle of repeated treatments.

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Instead: Organic Herbicide

“For total weed and grass control in areas such as driveways, patios, or garden beds, a non-selective herbicide is the solution,” says Kail. Utilizing a natural herbicide allows for quick results without harming beneficial pollinators—or the environment.

However, if your goal is to tackle weeds within your lawn without harming the grass, then you'll need a selective herbicide.

Dish Soap

Using a mixture of dish soap and vinegar can be a potent weapon in the fight against weeds. However, even a small amount can lead to runoff that will damage nearby crops and plants. This solution doesn’t discriminate—it can take out any vegetation it touches.

Instead: Hand Weed

It's unpleasant, but consistent hand weeding will help you tidy up your garden beds without disturbing the soil. Ultimately, this environmentally friendly method is the best way to manage weeds, as it removes the weed and it's entire root system.