Alkaline soil

Alkaline soil, also known as “sweet soil,” is characterized by a high pH, typically above 7, and often occurs in regions with low rainfall or where the underlying parent material, such as limestone or chalk, is rich in calcium carbonate. These soils are commonly found in arid or semi-arid climates and tend to be well-drained but may sometimes suffer from compaction and poor structure.

The high pH of alkaline soils affects nutrient availability, making certain essential elements like iron, manganese, and phosphorus less accessible to plants. This can lead to deficiencies such as chlorosis, where leaves turn yellow due to insufficient iron uptake.

Plants that thrive in alkaline soils are often well-adapted to its chemical characteristics. Popular choices include lavender, clematis, lilacs, and many Mediterranean herbs like rosemary and thyme.

Gardeners managing alkaline soils can adjust pH by incorporating sulfur or organic matter such as compost to gradually lower the pH. For better nutrient availability without altering the pH, foliar feeding with chelated micronutrients can be an effective solution. Alternatively, choosing plants naturally suited to alkaline conditions is often the most sustainable approach.