Do You Need to Add Lime to California Garden Soil?
The Verdict: Mostly busted. Most California soils are already neutral to alkaline, and adding lime can push pH dangerously high for your plants.
Why People Believe This
Garden advice from the eastern United States and the UK often recommends liming as a routine spring task. In regions with heavy rainfall, soils tend to become acidic over time, and lime corrects that. But California is not the East Coast. Gardeners here sometimes follow national advice without adjusting for local conditions, or they see lime on the shelf at the garden center and assume it must be needed.
What the Research Says
UC ANR publications note that most California soils range from pH 6.5 to 8.5, which is neutral to alkaline. The Mediterranean climate, with its dry summers and relatively low rainfall, means our soils do not leach calcium the way eastern soils do. UC Master Gardeners of Santa Cruz County specifically caution against adding lime without a soil test, because our coastal and valley soils typically sit right around pH 7.0. Adding lime to already-alkaline soil can lock out essential nutrients like iron, manganese, and zinc, leading to yellowing leaves and stunted growth.
There are exceptions. Some mountain soils in the Santa Cruz Mountains (especially under redwood canopy) can be slightly acidic, and blueberry beds intentionally acidified with sulfur might eventually need pH correction. But these are targeted situations, not routine maintenance.
What to Do Instead
Test your soil before adding anything. The UC Davis Analytical Laboratory offers affordable soil testing, or you can pick up a home pH test kit at your local nursery. If your test shows a pH below 6.0 (uncommon in most of our area), then a targeted lime application may be appropriate. For most Santa Cruz County gardens, the better investment is compost, which naturally buffers pH in either direction and feeds the soil food web at the same time.
This week: Order a soil test or pick up a pH test kit before you buy any amendments this season.
For more on understanding your soil, check out our free California Garden Planning Guide at Your Garden Toolkit.
