How does concrete’s alkalinity affect surrounding plant life in gardens?

Concrete's alkalinity can significantly impact surrounding plant life in gardens due to its high pH levels. When rainwater or irrigation flows over concrete surfaces, it absorbs alkaline compounds like calcium hydroxide, which then leaches into the soil. This raises the soil's pH, making it more alkaline and less suitable for many plants that thrive in neutral or slightly acidic conditions.

Plants sensitive to high pH, such as azaleas and blueberries, may struggle to absorb essential nutrients like iron and manganese, leading to yellowing leaves and stunted growth. Over time, prolonged exposure to alkaline conditions can weaken or even kill vulnerable species.

To mitigate these effects, gardeners can use barriers like plastic or gravel to limit concrete runoff, amend soil with organic matter to buffer pH, or choose alkaline-tolerant plants like lavender and yarrow. Regular soil testing helps monitor pH levels and ensures a balanced environment for healthy plant growth.