Weeds are pesky plants that can quickly take over gardens, lawns, and other cultivated spaces. They compete with desirable plants for water, nutrients, and sunlight. Once weeds become established, they can be very difficult to control. Many gardeners and landscapers resort to using chemical herbicides to kill weeds. However, these chemicals can be harmful to the environment. An alternative, eco-friendly method for stopping weeds is using salt. But does applying salt to weeds actually prevent them from growing back? Let’s take a look at the evidence.
How Salt Affects Plants
Salt creates an inhospitable environment for plants by drawing moisture out of plant cells. This causes the plants to become dehydrated and die. Salt also changes the osmotic pressure in plant roots, making it more difficult for them to absorb water and nutrients from the soil. An accumulation of salt in the soil can increase the salinity, or salt content, to levels that are toxic to plants.
Most plants cannot tolerate high concentrations of salt. Common table salt, or sodium chloride, is particularly damaging. A high enough concentration of salt will desiccate and kill all vegetation it comes into contact with, whether those plants are considered weeds or desirable garden plants.
Using Salt as an Herbicide
Because of its drying, desiccating effect on plants, salt has sometimes been used as a natural herbicide to kill weeds. Salt can be sprinkled directly on weeds or sprayed in a saltwater solution. The salt draws moisture out of the unwanted plants, causing dehydration and inhibiting growth.
Salt tends to work best on young, actively growing weeds. Mature plants with established root systems may be more resilient. Repeated applications may be necessary to fully kill established weeds. The amount of salt needed can vary based on the size and number of weeds being treated. Excessive amounts of salt can damage surrounding soil and desirable plants.
Does Salting Weeds Prevent Regrowth?
Applying salt to weeds will damage and kill existing weeds. However, salting typically does not provide long-term weed prevention. Here are some reasons why salting weeds may not stop them from growing back:
Salt Does Not Prevent New Weeds
While salting will kill existing weeds, it does not provide any residual activity to prevent new weed seeds from germinating. Any bare areas created by salting will be quickly colonized by new weed growth. Follow-up applications of salt would be needed to continually kill emerging weeds.
Salt Leaches from Soil
Salt is water soluble and will gradually leach out of soil with rain, irrigation, or other water movement. This means any inhibitory effects in the soil are temporary. As the salt concentration decreases over time, the area will again become hospitable for weeds.
Some Weeds Are Salt Tolerant
While many plants are sensitive to salt, some weeds are naturally tolerant of salty conditions. Halophytes, plants adapted to salty environments, may be less affected by salt applications. Weeds like purslane, lamb’s quarters, and pigweed can withstand salt levels that would kill other plants. Their growth may be stunted but they will likely recover.
Does Not Address Underlying Causes
Salting weeds fails to address the underlying reasons why weeds are present, like soil disturbance, competition from desirable plants, and nutrient availability. As long as those factors remain, conditions will continue to favor weed germination and growth.
Improving Efficacy of Salting for Weed Control
While salting alone may not provide sustained weed prevention, there are some ways to enhance its short-term effectiveness:
– Apply early before weeds are well established. Focus on stopping new growth.
– Use coarse crystal salt that will dissolve slowly and have a longer exposure time.
– Combine with other methods like cultivation, mulching, or pre-emergent herbicides for more lasting results.
– Repeat salting frequently to kill newly sprouted weeds.
– Target applications to problem spots instead of entire areas.
– Use heavier salt concentrations on stubborn weeds.
– Combine with drought stress by withholding irrigation after salting.
– Remove dead weeds promptly so new weeds cannot take advantage of bare areas.
Potential Drawbacks of Using Salt for Weed Control
While salt may seem like an affordable, natural alternative to commercial weedkillers, overuse of salt can cause unfavorable effects:
– Can leave white salt residue on surfaces.
– Excess applications may damage concrete, masonry, metal, and other materials.
– Can leach into groundwater or contaminate water sources.
– May change soil chemistry, structure, and fertility with repeated heavy use.
– Can build up in soil to levels toxic for plants.
– May harm beneficial soil microorganisms.
– Can damage sensitive nearby plants through soil contamination or drift.
– Presents safety concerns for pets who may ingest salt or salty runoff.
Conclusion
Applying salt to weeds will effectively kill existing vegetation by dehydrating plant tissues. However, salting does not provide any lasting weed prevention. New weeds will quickly take advantage of bare areas. Some weeds are naturally tolerant of salt. And rainfall will dissolve and leach away salt over time. To keep weeds from growing back, the underlying factors that promote weed growth must be addressed. This may include improving soil conditions, reducing disturbances, proper planting space, and timely cultivation and mulching. Used judiciously, salting can be one short-term tactic in an integrated weed management plan. But salt alone is not an effective long-term solution for stopping weeds from returning.
