As a home gardener, it's important to test soil pH because certain plants have specific pH requirements and won't thrive unless the soil pH falls within a particular range. pH measures the level of acidity in the soil and it affects a plant’s ability to absorb nutrients. If the soil pH level falls outside of a plant's recommended range, all the plant food and fertilizer in the world won’t help -- the plants can’t absorb nutrients.
Technically speaking, a soil pH test measures how many hydrogen ions are in the soil. On a scale of 1 to 14, a pH less than 7.0 is acidic, 7.0 is neutral, and anything higher than 7.0 is alkaline. Acidic or alkaline soil isn't necessarily bad; it all depends on the plants you're growing. Most plants can adapt to soil pH ranges from 6 to 7.5, but some plants have distinct requirements. For instance, blueberries require acidic soil in the range of 4.5 to 5.5 to produce berries while lavender tends to do best in alkaline soil about 8.0.
When to Conduct a Soil pH Test
Testing your soil's pH should be an item to include on your fall garden task checklist. Testing pH in the fall enables you to take steps to correct the pH before the next spring planting season. And, fall is a good time to note any weeds that have grown throughout the summer, which can also give you clues about your soil pH. For instance, dandelions, wild strawberries, and plantain proliferate in acidic soil while chickweed, Queen Anne's lace, and chicory favor alkaline soil.
Performing a soil pH test in the fall gives you plenty of time to plant a nitrogen-fixing cover crop (for mild winter climates) or to revise next year's planting plan to suit the pH reading. In the case of alkaline soil, you can lower the pH by adding organic materials, such as peat moss. Acidic soil can be neutralized by adding lime. The type and quantity of soil amendments depend on how much the pH needs to be raised or lowered.
Learn How to Conduct a Soil pH Test
Equipment / Tools
- Hand trowel
- Clean glassware
- Liquid measuring cup
- Distilled water
- Coffee filter
- pH testing kit
- Baking soda
Testing pH Using Kitchen Supplies
An acidic solution generally reacts when it's added to something basic. You can use vinegar (acidic) and baking soda (basic) for a do-it-yourself quick pH reading of your soil. This do-it-yourself test will reveal whether the soil is relatively acidic or alkaline and is recommended for those who have healthy gardens that might benefit from a little more targeted care.
Dig for a Soil Sample
Using a hand trowel, dig four to six inches below the soil surface to obtain a soil sample. Dig in several locations in your garden bed to obtain an average soil sample representative of the area.
Clean the Soil
Remove stones, sticks, and other debris from the soil. Be sure to break up any large clumps.
Add Soil and Water Together
Place approximately one cup of soil into a clean glass container, and add enough distilled water to turn the soil to mud.
Add the Vinegar
Add 1/2 cup of vinegar and stir the mixture. If the soil fizzes, foams, or bubbles, your soil is alkaline.
Repeat the Process if No Bubbling Occurs
Take a soil sample, clean it of debris, place it into a clean container, and use distilled water to turn it into mud.
Add the Baking Soda
Add 1/2 cup of baking soda and stir. If the soil fizzes, foams, or bubbles, your soil is acidic.
Testing pH Using Soil Strips
Testing with vinegar and baking soda can indicate which end of the pH scale your soil is leaning. But for an exact measurement, a soil pH testing kit provides more definitive results. You can purchase testing kits at most garden centers and through local cooperative extension offices.
Dig for a Sample
Using a hand trowel, dig four to six inches below the soil surface to obtain a soil sample.
Collect the Soil
Place one to three teaspoons of soil in a clean glass. Remove sticks, stones, and other debris.
Pour in Distilled Water
Fill the glass with distilled water to the same level as the soil sample.
Agitate the Soil
Vigorously stir or swirl the mixture. Let the solution rest for 30 minutes.
Drain the Sample
Pour the soil sample through a coffee filter and into another clean glass. Make sure that you are capturing the solids and allowing the liquid to pass through.
Use the pH Test Strip
Dip the test strip into the liquid. Pay close attention to the instructions on how long to leave the strip in the liquid. When the strip turns color, compare the color to the chart on the manufacturer's packaging to determine the pH.
Repeat the Process
Repeat the process several times with samples from different parts of your garden to determine an average pH.
Soil pH Testing Tips
If you test your soil using vinegar and baking soda and neither test produces much of an effect, your soil is probably in the neutral range. No further testing is needed.
You can mix soil from several different samples of a small garden for the vinegar-baking soda test. However, if you have a large garden, it is better to test several samples separately.
If it's difficult to successfully grow anything in your garden beds or your lawn is not thriving, it's best to send a soil sample to a professional soil testing lab to obtain a complete soil analysis. Based on the test results, the experts will make specific recommendations for soil amendments.
Soil Testing. University of Maryland Extension Website
Soil testing and soil testing labs. Umd.Edu.
Reducing Soil PH. Wisconsin Horticulture.
“Soil Sampling Instructions.” Rutgers.Edu, https://njaes.rutgers.edu/soil-testing-lab/pdfs/home/Home_and_Landscape_-_Soil_Sampling_Instructions.pdf
Soil Testing Laboratory. Rutgers.Edu.