A natural weed killer made from vinegar, salt, and dish soap kills weeds fast by drying out foliage, but it is nonselective and will damage any plant it touches.
A simple DIY spray made from household ingredients can knock back crabgrass or a dandelion in hours — provided you use it correctly and understand its limits. The most reliable recipe uses white vinegar (acid that burns leaves), table salt (dehydrates the plant), and dish soap (helps mixture cling to waxy surfaces). Applied on a hot, sunny day, visible wilting starts within an hour or two, and full dieback happens over the next day.
The Basic Recipe That Works
The most commonly tested DIY weed killer calls for three ingredients:
- 1 gallon of white vinegar (5% acidity works; 15%–20% horticultural vinegar is stronger but requires extra safety gear)
- 1 cup of table salt (standard iodized or non-iodized)
- 1 tablespoon of liquid dish soap (Dawn or any standard brand)
Pour the vinegar into a bucket or garden sprayer. Add salt and stir until mostly dissolved (some sediment is normal). Add dish soap last, then stir gently to avoid foaming. Use immediately. For smaller jobs, scale down: 1 quart vinegar, 1/4 cup salt, 1 teaspoon soap. The recipe’s acidity burns the waxy cuticle of leaves, salt draws moisture out, and soap breaks surface tension so spray spreads evenly.
How To Apply It For The Best Results
This is a contact killer, not a soil treatment. Success depends on coverage and conditions.
- Choose the right day. Apply when the forecast shows at least 24 hours without rain, temperatures above 70°F, and full sun. Heat and UV light speed up the burn.
- Aim precisely. Spray leaves and stems until fully saturated but not dripping. Shield nearby plants with cardboard or a plastic bag — the spray kills anything it touches.
- Watch for results. Leaves may curl and brown within 1–2 hours. Full dieback typically takes 24–36 hours. Established weeds with deep taproots may need a second application.
- Reapply as needed. Perennial weeds like bindweed or ground ivy often regrow from roots and require another treatment when new leaves appear.
Variations And Stronger Options
Several published recipes adjust ratios for tougher weeds:
- High-strength vinegar: Swap 5% for 15%–20% horticultural vinegar (farm supply stores). Keep 1 cup salt and 1 tablespoon soap per gallon. Safety note: 15%+ vinegar can cause chemical burns — wear goggles, rubber gloves, and a long-sleeved shirt; avoid breathing spray mist.
- With citrus oil: Add 1/4 cup orange or citrus oil to boost solvent effect on weed wax, improving knockdown on mature weeds.
- Without salt: On areas you’ll replant soon, skip salt or reduce to 1/4 cup, as salt can linger and harm future plantings. Vinegar and soap still kill foliage.
- Boiling water: For isolated weeds in cracks, a kettle of boiling water kills foliage on contact and works on annual weeds. Pour carefully — it scalds skin and can splatter.
What This Recipe Cannot Do
This spray is nonselective, so it fails as a lawn herbicide. Spraying clover in grass will kill the clover — and leave a brown dead spot. It also does not kill roots reliably. Annual weeds die above ground and are finished; perennial weeds often regrow from roots within a week or two, requiring repeated sprays. Repeated heavy salt use can build up in soil near driveways, creating a zone where nothing grows for months. The mixture also clogs sprayers if salt hasn’t fully dissolved. Rinse sprayer thoroughly after each use to prevent salt buildup.
FAQs
Does Epsom salt work better than table salt in weed killer?
Epsom salt (magnesium sulfate) dehydrates weeds the same way but is slower and less concentrated. Table salt is cheaper and more effective. Some gardeners prefer Epsom salt on garden beds since it adds magnesium, but the weed-killing effect is weaker.
Will rain wash away the spray before it works?
Yes. The mixture needs about 24 hours of dry weather to penetrate leaves. Rain within a few hours rinses it off, and the weed survives. Always check the forecast before mixing.
Can I use this on my lawn without killing the grass?
No. This nonselective spray kills any green tissue it contacts. Overspray onto turfgrass will brown and die within a day. For broadleaf weeds in a lawn, use a selective herbicide or manual pulling.
References & Sources
- This Old House. “DIY Weed Killer Recipe.” Provides the basic vinegar-salt-soap recipe and application instructions.
- Southern Living. “Homemade Vinegar Weed Killer Recipe.” Covers variations including Epsom salt and citrus oil.