How and When to Test Soil pH

Vinegar and kits with test strips are two dependable methods

Project Overview
  • Working Time: 30 - 45 mins
  • Total Time: 30 - 45 mins
  • Skill Level: Beginner
  • Estimated Cost: $20

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. A pH measurement checks the acidity level in the soil, affecting a plant's ability to absorb nutrients. If the soil pH level falls outside a plant's recommended range, all the plant food and fertilizer in the world won't help—the plants can't absorb nutrients.

digging soil up in a garden

The Spruce/Claire Cohen

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 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 an excellent 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.

What You'll Need

Equipment / Tools

  • Hand trowel
  • Clean glassware
  • Liquid measuring cup

Materials

  • Distilled water
  • Coffee filter
  • pH testing kit
  • Vinegar
  • Baking soda

Instructions

Testing pH Using Kitchen Supplies

An acidic solution reacts when added to something alkaline or 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.

Note

Compared to soil pH home kits, going through a soil testing lab is a sure way to get the most accurate results. Soil testing labs provide a complete soil composition analysis, including the percent of organic matter and major and minor nutrients, and pH level.

  1. Dig for a Soil Sample

    Dig four to six inches below the soil surface using a hand trowel to obtain a soil sample. Dig in several locations in your garden bed to get an average soil sample representative of the area.

    digging up soil
  2. Clean the Soil

    Remove stones, sticks, and other debris from the soil. Be sure to break up any large clumps.

    removing sticks from soil
  3. 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 into mud.

    adding water to soil
  4. Add the Vinegar

    Add 1/2 cup of vinegar and stir the mixture. Your soil is alkaline if the soil fizzes, foams, or bubbles.

    adding vinegar to the soil
  5. 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.

    adding water to soil
  6. Add the Baking Soda

    Add 1/2 cup of baking soda and stir. Your soil is acidic if it fizzes, foams, or bubbles.

    adding baking soda to soil

How to Raise or Lower pH

Raising or lowering pH can start instantly by adding amendments to your soil. To make your soil more alkaline (increase the pH), add garden lime (limestone) or bone meal. To increase acidity (lower the pH), add soil acidified (sulfur) or peat moss. Remember that your soil will revert to its original state, so test the pH periodically; you'll likely need to add more amendments to keep the pH where you need it to be.

Testing pH Using Soil Strips

Testing with vinegar and baking soda can indicate which end of the pH scale your soil is leaning. But a soil pH testing kit provides more definitive results for an exact measurement. You can purchase testing kits at most garden centers and through local cooperative extension offices.

  1. Dig for a Sample

    Dig four to six inches below the soil surface using a hand trowel to obtain a soil sample.

    Digging for a soil sample

    The Spruce / Almar Creative

  2. Collect the Soil

    Place one to three teaspoons of soil in a clean glass. Remove sticks, stones, and other debris.

    Collecting the soil in a glass bowl

    The Spruce / Jayme Burrows

  3. Pour in Distilled Water

    Fill the glass with distilled water to the same level as the soil sample.

    Pouring distilled water into the glass bowl

    The Spruce / Jayme Burrows

  4. Agitate the Soil

    Vigorously stir or swirl the mixture. Let the solution rest for 30 minutes.

    Agitating the sample with water

    The Spruce / Jayme Burrows

  5. Drain the Sample

    Pour the soil sample through a coffee filter and into another clean glass. Make sure you capture the solids and allow the liquid to pass through.

    Straining the sample through a coffee filter

    The Spruce / Jayme Burrows

  6. 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.

    Dipping the pH test strip into the liquid

    The Spruce / Jayme Burrows

  7. Repeat the Process

    Repeat the process several times with samples from different parts of your garden to determine an average pH.

    Repeating the testing process

    The Spruce / Jayme Burrows

How to Test Soil pH With a Meter

A soil pH meter is one of the easiest methods for testing pH. These soil pH probes are simple—push the skewer-like, pointy metal probe into the soil or a cup with a soil sample. The depth varies depending on the meter manufacturer. With some probes, you get results instantly; others might take a minute. Some probes test more than pH, like soil moisture, sunlight, and temperature.

These digital and analog probes require no test strips, mixing of ingredients, or much time. Some meters might require adding water to the cup. For best results, follow the package instructions.

Tip

As with any product on the market, not all products are created equal. Some are more reliable than others. Review customer reviews and expert advice on soil meters before purchasing a product. For more accuracy, do more than one test to compare results. If the two independent tests align, it's a good indicator you're on the right track.

Soil pH Testing Tips

  • If you test your soil using vinegar and baking soda and neither test produces many effects, your soil is probably in the neutral range. No further testing is needed.
  • You can mix soil from several samples of a small garden for the vinegar-baking soda test. However, it is better to test several samples separately if you have a large garden.
  • If it's difficult to grow anything in your garden beds or your lawn is not thriving, sending a soil sample to a professional soil testing lab is best to obtain a complete soil analysis. The experts will make specific recommendations for soil amendments based on the test results.
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  1. Soil Testing. University of Maryland Extension Website

  2. Soil testing and soil testing labs. Umd.Edu.

  3. Reducing Soil PH. Wisconsin Horticulture.

  4. “Soil Sampling Instructions.” Rutgers.Edu, https://njaes.rutgers.edu/soil-testing-lab/pdfs/home/Home_and_Landscape_-_Soil_Sampling_Instructions.pdf

  5. Soil Testing Laboratory. Rutgers.Edu.