How to Conduct a Soil pH Test

digging soil up in a garden

The Spruce/Claire Cohen

Overview
  • Total Time: 60 mins
  • Skill Level: Beginner
  • Estimated Cost: $20

As a home gardener, it's important to test your soil pH. Certain plants can only access the soil's nutrients if the pH is within a certain range. And not even additional plant food or fertilizer will help if your soil lies outside of a plant's preferred pH range. Technically speaking, a soil pH (potential hydrogen) test measures how many hydrogen ions are in the soil. A pH less than 7 is acidic, 7 is neutral, and anything higher than 7 is alkaline. Acidic or alkaline soil isn't necessarily bad; it all depends on what you're growing. Most plants can adapt to soil pH that ranges from 6 to 7.5, but some plants have distinct preferences. For instance, blueberries prefer acidic soil while asparagus tends to do best in alkaline.

When to Do a Soil pH Test

Testing your soil's pH should be a fall garden checklist item. That way, you can amend the soil before winter or first thing in the spring before you plant. Plus, this 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.

Moreover, performing your soil pH test in the fall gives you plenty of time to plant a nitrogen-fixing cover crop (for mild winter climates) or to tweak next year's planting to suit your 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 quantity you add depends on how much you need to change your pH.

What You'll Need

Equipment / Tools

  • Hand shovel
  • 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 generally reacts when it's added to something basic. Thus, you can use vinegar (acidic) and baking soda (basic) to give you a quick pH read of your soil. This test will uncover the general soil composition and is recommended for those who have relatively healthy gardens that might benefit from a little more targeted care.

  1. Dig for a Soil Sample

    Using a hand shovel, dig 4 to 6 inches below the surface of your garden to obtain a soil sample.

    digging up soil
  2. Remove Stones, Sticks, and Other Debris From the Soil

    Also be sure to break up any large clumps.

    removing sticks from soil
  3. Add Soil and Water Together

    Place approximately 1 cup of soil into a clean glass container, and add enough water to turn the soil to mud.

    adding water to soil
  4. Add 1/2 Cup of Vinegar, and Stir Slightly

    If the soil fizzes, foams, or bubbles, your soil is alkaline.

    adding vinegar to the soil
  5. If No Bubbling occurs, Repeat the Process

    Take a soil sample, clean it of debris, place it into a clean container, and turn it to mud.

    adding water to soil
  6. This Time, Add 1/2 Cup of Baking Soda, and Stir Slightly

    If the soil fizzes, foams, or bubbles, your soil is acidic.

    adding baking soda to soil

Testing pH Using Soil Strips

Testing with vinegar and baking soda can tell you on which end of the pH scale your soil is leaning. But for an exact measurement, a soil pH testing kit is the way to go. You can purchase testing kits at most garden centers and through local cooperative extension offices.

  1. Dig for a Sample

    Using a hand shovel, dig 4 to 6 inches below the surface of your garden to obtain a soil sample.

  2. Place 1 to 3 Teaspoons of Soil in a Clean Glass

    Remove sticks, stones, and other debris.

  3. Pour in Distilled Water

    Fill the Glass with Distilled Water to the Same Level as the Soil Sample

  4. Agitate the Soil Vigorously by Stirring or Swirling

    Then, let the solution rest for 30 minutes.

  5. Pour 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.

  6. Dip the pH Test Strip into the Liquid

    Compare the color it turns to the chart on the manufacturer's packaging to determine the pH.

  7. 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 three or four 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.

For garden soil that won't grow anything, it's best to send a soil sample to a lab for testing for a nominal fee. Then, based on the results, the experts can make recommendations to get you back on track.