How long does salt take to kill weeds?

How Long Does Salt Take to Kill Weeds?

Salt typically takes 3-10 days to show visible effects on weeds. The exact timeframe depends on weather conditions, the type of weed, and how much salt you’ve applied. In ideal conditions (dry weather, warm temperatures), you might see wilting within 3-4 days. In less favourable conditions, it can take the full 10 days or longer.

That said, “showing effects” and “killing permanently” are very different things. Salt is a contact-based treatment that primarily damages the visible parts of weeds while leaving root systems intact. So while you’ll see results within that 3-10 day window, you’ll often see regrowth within a few weeks. For the full picture on salt as a weed killer, see our complete guide: Does Salt Kill Weeds?

The Salt Timeline

Day 1-2: Little visible change. The salt is dissolving (if it rains or there’s moisture) and beginning to be absorbed by the plant. You might notice the weeds looking slightly stressed.

Day 3-5: First signs of damage appear. Leaves begin to yellow and brown at the edges. The plant starts to wilt as the salt draws moisture out of its cells through osmosis.

Day 7-10: Maximum visible damage. The above-ground parts of the weed should look thoroughly dead – brown, shrivelled, and crispy. At this point, most gardeners assume success.

Week 3-4: The disappointment phase. Fresh green shoots emerge from the base of many “dead” weeds. The roots survived, and the plant is regenerating. Back to square one.

Factors That Affect Timing

Weather is critical. Salt needs to stay in contact with the plant to work. Rain washes it away before it can be fully absorbed, essentially resetting the clock. Apply on a dry day with no rain forecast for at least 3-4 days for best results.

Weed type matters enormously. Small, shallow-rooted annual weeds may actually die within that 10-day window. Deep-rooted perennials like ivy, brambles, and nettles will show surface damage but almost always regrow. Their extensive root systems simply aren’t affected by salt applied to the leaves.

Application method influences speed. Dry salt sprinkled directly onto weeds relies on rain or dew to dissolve it and carry it into the plant – this is slower but more concentrated. Salt dissolved in water and sprayed on works faster initially but is more diluted. Either way, the fundamental limitation remains: salt doesn’t reach roots.

Salt on Different Surfaces

Hard surfaces: Salt works best on block paving, driveways, and patios where you don’t care about soil health. Weeds in paving cracks are often smaller and more exposed, making them more vulnerable to salt treatment. Expect visible results within 7-10 days for small weeds.

Gravel areas: Gravel driveways can be treated with salt, but results are less predictable. The salt disperses into the gravel and may not concentrate around the weeds effectively. You may need multiple applications.

Garden beds: Don’t use salt anywhere you want to grow plants in future. It persists in soil and will prevent anything from growing for months or even years. If you need to treat weeds in planting areas, a proper weed killer that breaks down after doing its job is a much better choice.

Why Waiting Isn’t Worth It

Here’s the uncomfortable truth about salt’s timeline: you’re waiting 3-10 days for results that probably won’t last. Compare this to a long-lasting weed killer that takes a similar amount of time but actually kills weeds permanently, roots and all.

With salt, you’re essentially on an endless cycle: apply, wait 10 days, see results, wait 3 weeks, see regrowth, apply again. With a systemic herbicide containing glyphosate, you apply once, wait 2-3 weeks, and the weed is gone for good.

For tough perennial weeds like bamboo or established ivy, salt simply isn’t a realistic option regardless of how long you wait. These plants have underground root networks that can extend for metres – no amount of surface salt treatment will ever reach them.

If You Still Want to Try Salt

We’re not here to tell you what to do. If you want to try salt, apply it generously on a dry day, be patient for at least 10 days, and understand that you’ll likely need to repeat the process. For small weeds on hard surfaces, it can work as a cheap maintenance method if you’re willing to reapply regularly.

Other homemade weed killer options like vinegar work faster (24-48 hours) but share the same limitation of not killing roots. Bleach is more aggressive but comes with surface damage and environmental concerns. Boiling water works instantly but cools too quickly to affect roots.

For more on how salt compares to other methods, see: Does Salt Kill Weeds?