Reference
Understanding Soil pH (and How to Test It)
The short answer
Soil pH measures how acidic or alkaline your soil is, on a scale from about 3.5 to 9. It matters because it controls whether nutrients in the soil are actually available to plant roots — most vegetables and lawns do best in slightly acidic to neutral soil (about pH 6.0-7.0). A blueberry, which needs strongly acidic soil, is the classic exception.
Test before you adjust. A soil test (an inexpensive lab test through your county Extension office, or a home kit for a rough reading) tells you your pH and gives a specific recommendation. Adding lime to raise pH or sulfur to lower it without a test is guesswork — follow the test's rate, not a generic number.
Why pH matters
Nutrients don't work in isolation — their availability rises and falls with pH. In soil that's too acidic or too alkaline, nutrients get 'locked up' and plants show deficiency symptoms even when the nutrient is present. Getting pH into the right range for your crop is often more effective than adding fertilizer.
How to test
- 1Lab test (best) — A soil test through your county Extension gives an accurate pH plus a tailored recommendation for how much lime or sulfur to add, if any.
- 2Home kit (rough) — Inexpensive kits and meters give a ballpark reading — useful for a quick check, less precise than a lab.
Adjusting pH — carefully
To raise pH (make less acidic) you add lime; to lower it (make more acidic) you add elemental sulfur. Both act slowly, over months, and the right amount depends on your soil type and starting pH — which is exactly what the soil test tells you. We don't publish a one-size lime or sulfur rate, because the correct amount is soil-specific.
⚠ Don't guess at lime or sulfur amounts — over-correcting is hard to undo. Use the rate from a soil test, and re-test after a season.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- Washington State University Extension — Soil Testing (home garden) — Soil pH affects nutrient availability; test soil to determine pH and follow the test's specific recommendations for lime or sulfur rather than guessing.
- University of Maryland Extension — Organic Matter and Soil Amendments — Most vegetables grow best around pH 6.0-7.0; a soil test determines pH and the amendment needed.