The presence of weeds in paver joints is a common issue for homeowners seeking a tidy outdoor space. Many people look for non-toxic, readily available alternatives to conventional herbicides to address this problem. Baking soda, known chemically as sodium bicarbonate, is a popular and inexpensive household product often considered a do-it-yourself solution for killing weeds between pavers. It offers a simple way to combat the nuisance weeds that sprout up in cracks and crevices without introducing harsh chemicals.
How Baking Soda Kills Plants
Sodium bicarbonate kills vegetation primarily through two distinct chemical actions: desiccation and pH alteration. The sodium component acts like a salt, disrupting the water balance within the plant’s cells, a process known as osmosis. When applied to the foliage, the sodium draws out moisture, dehydrating the plant’s leaves and stems until they wither and die.
The second mechanism involves raising the soil’s alkalinity, creating a high pH environment. Baking soda, which is mildly alkaline, makes the joint sand or soil inhospitable for most weeds to thrive. This dual action is most effective on young, shallow-rooted annual weeds, like chickweed, that are easily affected by surface treatments. Deep-rooted perennial weeds, such as dandelions, are often more resilient, as baking soda may only kill the top growth, allowing the root system to resprout later.
Step-by-Step Application Guide
Effective application begins with preparing the area, which involves clearing away any large, established weeds by hand to ensure the treatment reaches the joint sand. Apply the baking soda on a dry, calm day, as rain or wind can wash away or scatter the powder, reducing its effectiveness. Applying the product in a dry form is the most direct method for paver cracks.
To use the dry method, lightly dampen the existing weed foliage so the powder adheres to the plant. Sprinkle approximately one teaspoon of baking soda directly onto each weed or generously over the affected paver joint. Use a stiff broom to gently sweep the sodium bicarbonate deep into the cracks and crevices where the weed roots are located.
Alternatively, for more targeted coverage, a liquid solution can be made. Mix about one cup of baking soda into a gallon of water, possibly adding a few drops of dish soap to help it stick to the leaves. This liquid is then carefully poured or sprayed directly onto the target weeds in the paver joints.
Impact on Pavers and Nearby Vegetation
While baking soda is an effective weed killer, its non-selective nature means it can also harm desirable plants, including lawn grass and garden beds, if runoff occurs. The high sodium content can leach into adjacent soil, causing salt buildup that degrades soil health and makes it difficult for other plants to grow. Using a piece of cardboard as a shield when applying the solution can help protect nearby landscaping from accidental contact.
Baking soda is generally safe for cleaning concrete and stone surfaces, and it is sometimes used as a mild abrasive in cleaning pastes. However, excessive or frequent application relies on altering the chemistry of the joint environment. This change in soil alkalinity and salinity may affect the surrounding joint sand or polymeric sand over time, which is important for paver stability. Since baking soda provides a surface treatment and does not destroy deep roots, reapplication every four to six weeks may be necessary to suppress new weed growth.