Adjust soil pH with lime or sulfur

Apply garden lime (calcium carbonate) to raise pH in acidic soil, or elemental sulfur to lower pH in alkaline soil. Most vegetables grow best at pH 6.0-7.0. Apply at the rate recommended by a soil test and work into the top several inches of soil.

Why It Works

Soil pH controls nutrient availability. Even if nutrients are present in the soil, plants cannot absorb them efficiently at the wrong pH. Iron, manganese, and zinc become unavailable in alkaline soil; phosphorus and calcium become limited in very acidic soil. Correcting pH unlocks nutrients that are already there.

Tips

• Always test pH before amending — adding lime or sulfur without knowing your current pH can make things worse
• Dolomitic lime also adds magnesium; calcitic lime adds only calcium
• pH changes take 2-3 months to fully develop — amend in fall for spring planting when possible
• Wood ash raises pH (and adds potassium) but is difficult to dose precisely