Chalky (Alkaline) Soil
Soil Type
Chalky soil, sometimes called alkaline or calcareous soil, is common in areas with limestone or chalk bedrock. It has a naturally high pH and often contains visible chunks of pale stone. Gardeners working with this soil may notice that certain plants struggle while others thrive.
What it is
Chalky soil is usually pale, stony, and free-draining, and it can be either light and sandy or heavier and more clay-like. Because it is rich in calcium carbonate, its pH sits on the alkaline side, generally above 7. Water tends to pass through it quickly, so it can dry out fast in warm weather and is often low in organic matter. The high pH can also make nutrients such as iron and manganese less available, which sometimes appears as yellowing between the leaf veins on sensitive plants.
What to do
Add generous amounts of organic matter, such as compost or well-rotted leaf mold, to help the soil hold moisture and support nutrient availability. Keeping a layer of mulch on the surface slows rapid drying and feeds the soil as it breaks down over time. Rather than trying to change the pH of a whole yard, it is often easier to select plants that naturally tolerate alkaline conditions. For acid-loving plants, growing them in containers or raised beds with a suitable growing mix is usually more practical than reworking open ground.
Tips
Have your soil tested through your local Cooperative Extension office so you know your actual pH and can receive guidance suited to your region. Extension staff can help you interpret the results and suggest appropriate amounts of any amendment for your specific conditions. In most cases, working with the soil you have rather than against it gives the steadiest long-term results.
General guidance for US gardens. For specific nutrient, pH, and amendment rates, have your soil tested through your local Cooperative Extension office. Page updated Aug 4, 2026.