Does Diesel Kill Weeds? Efficacy Explained

Weeds are a nuisance whether they are growing on your driveway, patio, on the lawn, or in the soil prepared for planting. If left untreated, they become an eyesore or worse, will strangulate the roots of the healthy plants and grass.

You might think that diesel is an effective weed killer, but have concerns over its use.

Diesel fuel is toxic to all plant material and, as such, kills any unwanted weeds and grasses.

Although it is highly effective when used with extreme care. Accidental spillage or spraying will also cause healthy plants and shrubs to wither and die.

Diesel is only effective for one season. The weeds will have already dropped seeds in the soil that are protected by hard husks and shells that the diesel cannot penetrate. Therefore, the following spring, the seeds will germinate, weeds grow, and so the cycle begins again.

How to Use Diesel to Kill Weeds

The task is best undertaken early in the morning on a still, dry day where no rain is forecast.

  • Use a funnel to decant diesel from its storage container into a spray bottle. Ensure the bottle has a direct spray function to attack the target area and avoid the surrounding areas.
    • Diesel has a thick viscosity and requires the appropriate nozzle for the liquid to flow freely.
  • Get down close to the affected area and spray liberally directly on the roots. If you're aiming at a crack in slabs, apply directly into the gap.
  • Do not overspray; any excess will run away and potentially kill healthy plants.
  • Return any unused diesel to the main container. Label the spray bottle to avoid hazardous cross-contamination.

The Effect Diesel has on Plants

does diesel kill weeds

Weed and grass species react differently to diesel; some are more tolerant than others.

Rough meadow grasses have a particular intolerance and die off quickly.

Some of the hardier, more substantial weeds may require a second dousing if there is no sign of their decline within 24-hours.

How Long Before the Diesel Takes Effect

You should notice wilting and signs of discoloration within a few short hours of treatment.

Wait for 48-hours before clearing the area of any dead weeds; if possible, also remove the top inch of soil. It will not only rid the zone of most of the diesel but also of seeds in the soil.

If there has been an accidental spillage of diesel, take at least 6-inches of the contaminated soil.

Is Diesel a Permanent Solution to Weed Problems

Although toxic diesel kills the leaves, stems, and roots of weeds, the seeds remain. Without the intervention of another weedkilling method, the weeds will return the following season.

Any diesel in the soil is either removed when the dead weeds are cleared or washed away, diluting the effectiveness.

Traces of diesel remaining in the soil that might otherwise pollute the environment become a source of energy for naturally occurring micro-organisms.

This process is known as bioremediation and relies on fungi, bacteria, and yeast to convert toxic substances into less harmful ones. With the soil free from contaminants, seeds can once again germinate.

Is it Safe to Use Diesel to Kill Weeds?

It is not advisable to use diesel for weedkilling if your property relies on water from a well. If allowed to soak into the soil in great quantities, it will leach into the water supply, causing contamination.

Vapors and toxic fumes are harmful to your yard and the environment; if used in the correct manner and quantity, diesel is safe. If you have further concerns, wear a face mask and use the diesel sparingly.

Diesel is a combustible liquid with a higher flashpoint than gasoline, which is flammable.

Although diesel does burn, it won't burst into flames; instead, it takes time to get going.

Diesel should be stored safely, in a cool, dry area, and with a tightly-sealed cap. Only buy and keep as much as you need.

When stored and used carefully, diesel is not a fire hazard.

Is Diesel Harmful to the Garden

Diesel kills anything in its path, including plants and flowers that you wish to keep. We recommend using a different, less intrusive method to remove weeds in flower beds and patches.

Using diesel to kill weeds is a double-edged sword; it also kills bugs and micro-organisms in the soil, many of which are beneficial. These life-forms maintain its health and acidity levels, ensuring it is a hospitable place for things to grow.

Ways to Avoid Using Diesel as a Weed Killer

weeds in garden

Establishing a good gardening regime often prevents weeds from growing.

  1. Leave grass longer; the shade creates an environment that weeds find difficult to grow in.
  2. Water deep twice a week. The roots of the grass will grow long and strong, crowding out any germinating weeds.
  3. Try organic methods, such as mulching, solarizing, or using boiled water.
  4. Use two-layers of weed control beneath the bark, stone chippings, paved areas.

Final Thoughts

It is advisable to remove weeds before they cause irreparable, irreversible damage to your yard.

Using diesel to kill weeds is a safe and effective method in small areas.

However, it isn't a long term solution; other non-toxic methods and products are worthy of consideration.

Although using diesel is an inexpensive and effective option to clear weeds from between paving stones and chippings, it renders soil out-of-action for new planting for long periods.

Annette Marsh
For the past twenty years, Annette has allocated much of her free time towards gardening and landscaping related tasks; Planting flowers and trees, weeding, pruning, mulching, mowing, constructing ponds and various other structures, as well as growing and maintaining a vegetable garden.

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Seeds N' Flowers shares actionable gardening advice in the form of informational guides. We cover Plants, Flowers, Trees, Tools, and more