The Famous Recipe: Salt + Vinegar + Dish Soap = Soil Damage + Failure.
This Pinterest favourite can kill small annual weeds – but the salt damages your soil for months or years, and established weeds with root systems simply regrow. You might clear some seedlings while making the ground toxic for anything else you want to grow.
The Salt, Vinegar, and Dish Soap Weed Killer Recipe
This is perhaps the most shared homemade weed killer recipe on social media. Combining salt, vinegar, and washing up liquid creates an aggressive contact treatment that does kill small weeds – but comes with serious downsides that Pinterest posts rarely mention.
The Recipe
The typical formula:
Ingredients:
- 1 gallon (4 litres) white vinegar
- 1 cup (250g) table salt
- 1 tablespoon washing up liquid
Method:
- Dissolve salt in vinegar (may need warming)
- Add dish soap and mix gently
- Transfer to spray bottle or watering can
- Apply directly to weed foliage on dry, sunny days
How Each Ingredient Works
Vinegar (acetic acid): Burns plant tissue on contact. Causes rapid browning and wilting of leaves. Cannot travel to roots.
Salt (sodium chloride): Dehydrates plant cells by drawing out water. Also poisons soil, preventing plant growth until rain leaches it away – which can take months or years.
Dish soap (surfactant): Helps the solution spread across waxy leaves and stick rather than beading up. Improves coverage but has no weed-killing properties itself.
What It Can Kill
To be fair, this recipe does work on certain targets:
Annual weed seedlings. Young weeds without established root systems can be killed by destroying their foliage.
Small weeds in paving. Weeds in cracks with minimal soil are vulnerable to this aggressive treatment.
Tender new growth. Fresh, soft growth is more susceptible than tough, mature foliage.
If you spray this on tiny weeds on a hot, sunny day, you’ll see results within hours.
The Soil Damage Problem
Here’s what the Pinterest posts don’t mention:
Salt doesn’t break down. Unlike vinegar which dissipates quickly, salt persists in soil. It doesn’t decompose or evaporate – it stays until rain slowly leaches it away.
Creates a dead zone. Salt-contaminated soil won’t support plant growth. Use this recipe in a border, and you may not be able to grow anything there for months.
Spreads with water. Salt dissolves and moves with rainwater. It can spread beyond your target area, damaging nearby plants and lawn.
Accumulates with repeated use. Each application adds more salt. Regular use builds up soil contamination over time.
Why Established Weeds Survive
Despite being more aggressive than vinegar alone, this recipe still fails on established perennial weeds:
Roots remain untouched. The mixture only affects tissue it contacts directly. Underground roots, taproots, and rhizomes sit safely below the surface.
Energy reserves fuel regrowth. Perennial weeds store energy in their root systems. Burn the leaves, and they draw on these reserves to produce new growth.
Deep roots escape salt damage. While salt harms shallow soil, deep taproots like those of dandelions extend below the affected zone.
Spreading roots bypass treated areas. Bindweed and ground elder can regenerate from roots outside your treatment zone.
Honest Assessment
This recipe works for:
- Annual weed seedlings you want to kill quickly
- Path and patio weeds where soil health doesn’t matter
- Areas you never intend to plant
This recipe fails for:
- Any established perennial weed
- Borders or beds where you want to grow plants
- Areas near lawns (salt spreads)
- Long-term weed control (weeds regrow, soil remains damaged)
Better Options
If you want DIY weed control without soil damage:
Vinegar and dish soap only: Skip the salt. Less effective but doesn’t poison your soil. Suitable for path maintenance.
Boiling water: Kills on contact, no residue at all. Impractical for large areas but perfectly safe.
For actual weed elimination:
Systemic herbicide: Absorbs through leaves, travels to roots, kills the entire plant. Breaks down in soil without persistent damage. More effective and safer for your garden than salt.
Professional strength weedkiller: For tough weeds with deep root systems, commercial products deliver results that kitchen ingredients never will.
Long-lasting weed control: For paths where you want weeds gone for months, residual weedkillers work without the soil damage that salt causes.
The Verdict
The salt, vinegar, and dish soap recipe is genuinely effective at killing small annual weeds – but it’s a trade-off. You get quick results on easy targets while potentially damaging your soil for extended periods. Established weeds with root systems survive anyway, leaving you with dead soil and living weeds.
For paths and patios where you never want anything to grow, it’s an option. For anywhere else, the soil damage isn’t worth the limited weed control.
Pinterest Recipes, Real-World Disappointment
Salt damages soil for months. Established weeds survive anyway. For effective weed control without garden damage, use proper weedkiller.
