Im working on getting my blueberry patch acidified properly, and Ive noticed that the pH keeps drifting upwards (I suspect the buffered municipal water I irrigate with is the cause).
At any rate, Im looking for recommendations for an inexpensive soil pH test kit, since I wont be using these too frequently. Can pH test strips be used to test soil acidity?
Colorimetric test strips have long been used to gauge soil pH. I suggest purchasing from a local nursery with knowledgeable staff rather than online. Tests purchased from an online vendor might be old and of questionable quality.
Testing your soil’s pH is one of the most important things you can do as a gardener. Knowing whether your soil is too acidic, too alkaline, or just right allows you to make adjustments to optimize plant growth. While sending samples to a lab provides the most accurate results, testing strips offer a quick, easy, and affordable way to get a general sense of your soil’s pH right at home.
What is Soil pH and Why Does it Matter?
pH is a measure of how acidic or alkaline a substance is It ranges from 0 to 14, with 0 being extremely acidic, 7 being neutral, and 14 being extremely alkaline Most plants grow best when the soil pH is slightly acidic, between 6.0 and 7.0. If the soil pH drifts too far above or below this range, vital plant nutrients become unavailable for uptake through the roots. Extreme pH imbalance can prevent plants from absorbing any nutrients at all, leading to deficiency and death.
By testing soil pH, gardeners can determine if adjustments need to be made. Acidic soils can be raised by adding lime, while alkaline soils can be lowered with elemental sulfur. Getting the pH within the optimal range ensures plants can access the nutrients they need for vigorous growth.
How to Test Soil pH With Strips
Test strips provide a simple, fast way to check soil pH They are inexpensive, widely available, and allow for testing right in your garden Here’s how to use them
Gather Your Materials
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pH test strips – Available at garden centers, hardware stores, and online. Look for a wide range like 2.5 to 9 to cover acidic to alkaline soils.
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Distilled water – Tap water may skew results so distilled is best for mixing with soil
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A clean container – Like a plastic cup or jar.
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A stick or spoon – For mixing the soil and water.
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A notepad – To record your test strip results.
Take a Soil Sample
Collect soil from around 6-8 inches deep from the area you want to test. Take samples from a few spots and mix together in your container. Remove any rocks, debris, or plant material.
Mix the Soil Sample
Add distilled water to your soil, a little at a time, mixing continuously until you achieve a thick, smooth mud that drips easily off the stick. The soil should crumble if squeezed gently in your fist.
Dip the Test Strip
Dip just the very end of the test strip into the soil mixture, holding for 10-30 seconds. Don’t immerse the whole strip or leave in too long.
Check the Color Change
Compare the strip color to the chart on the package, under good lighting. Match it as closely as you can to determine the pH. The color may continue to develop so read it promptly.
Record and Repeat
Note the result and repeat the process with fresh strips and samples from around the garden. Take several readings and average them. Testing over time shows how pH changes seasonally.
Factors That Affect Soil pH Test Accuracy
While pH strips provide a good ballpark figure, they aren’t as precise as lab testing. Use care when sampling and testing to get the best home results:
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Follow package directions closely, from storage to procedure.
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Only use fresh strips within the expiration date. Old strips lose accuracy.
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Test multiple samples from around the garden and average results.
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Use distilled water as tap water mineral content varies.
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Mix soil and water thoroughly to an even consistency.
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Work with clean hands and containers to avoid contamination.
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Record results right away before color continues to develop.
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Consider time of year and recent amendments that could alter pH.
Interpreting and Using Your Soil pH Results
Once you’ve tested, what do the results mean and what should you do about them? Here are some general guidelines:
Extremely Acidic: pH 5.5 and below
- Nutrient deficiencies likely.
- Add lime to raise pH.
Slightly Acidic: pH 5.5-6.5
- Ideal for vegetables and fruits.
- Monitor and maintain.
Neutral: pH 6.5-7.0
- Optimal for most plants.
- Monitor and maintain.
Slightly Alkaline: pH 7.0-7.5
- Availability of some nutrients decreases.
- Add elemental sulfur or peat moss to lower pH.
Extremely Alkaline: pH 7.5 and above
- Nutrient deficiencies likely.
- Add sulfur to reduce pH.
Fluctuating Results
- Can indicate unstable or unhealthy soil lacking in organic matter.
- Incorporate compost to buffer pH changes.
Adjusting soil pH is a slow process so make additions well before each growing season and retest annually. Contact your local extension office for specific recommendations based on your soil test results.
The Benefits of Testing Soil pH
While numbers don’t tell the whole story, taking a few minutes to periodically test soil pH can alert you to developing issues and allow you to take corrective action. Think of it as taking your soil’s vitals. By providing a snapshot of the foundational growing conditions, it allows you to be a more informed, intuitive gardener. Addressing pH problems early helps prevent lackluster performance and lost crops down the road.
Understanding pH also builds your knowledge of the complex, living system right below our feet – the soil ecosystem. This encourages us to nurture not just our plants, but the organic matter, microorganisms, and mineral balance of the soil as well.
While pH strips aren’t perfect, they make a great addition to every gardener’s toolbox. Used properly and in combination with other observations of your soil and crops, they provide valuable insight into the hidden world under your garden.
Related content Photo Credit: Sergey – Adobe Stock (Cropped from original)
Q: Contact your local Master Gardeners for information on soil testing near you.
Kerry Locke, Donald A. Horneck, John M. Hart, Robert G. Stevens | Jul 2021 | OSU Extension Catalog Peer reviewed (Orange level)
John M. Hart, Donald A. Horneck, Robert G. Stevens, Neil Bell, Craig G. Cogger | Jul 2021 | OSU Extension Catalog Peer reviewed (Orange level)
Want to learn more about this topic? Explore more resources from OSU Extension:
Soil acidity can be determined from pH testing strips, but the measurements may not be as accurate as using a meter or bringing a soil sample to a testing site. Photo Credit: AlDa.videophoto – Adobe Stock
Tips for using pH testing strips
- pH strips are likely not quite as accurate as a meter. If you seem to be tracking a trend, such as if the true answer is 5.3 or 5.1, the test is still giving you information you can compare to the last test. I question the validity of any pH test that gives more than 1 decimal place.
- Measure the soil and water very carefully. Follow the package directions exactly. pH is a measure of H+ concentration in solution, so sloppy measurements will give information thats not meaningful.
- Proper storage will extend the life of the strips. The package will have directions about how to store the strips and these should be followed closely.
- Soil pH fluctuates on an annual cycle. Because of this, you cant compare readings from samples in the fall with readings from samples collected in the spring.
- Changing soil pH is a slow process. To change pH, it is recommended to apply sulfur to lower pH or agricultural lime to raise pH. It is encouraged to apply these materials in the fall, to give the chemical reaction more time to work.
Learn more about producing blueberry culture, soil acidification, and soil sampling in the following publications:
How to Use pH Litmus Strips to Measure pH in Vegetable Garden Soil – The Rusted Garden 2013
FAQ
Can I test soil pH with pH strips?
Unless you know the problems in your garden soil, you are only guessing when you apply fertilizer. Most plants grow best in a soil that is neither too acid nor too alkaline. Using test strips are an easy way to test the garden yourself for pH and nitrogen.
What is the most reliable way to test soil pH?
A calibrated meter is hard to beat and will likely always be the most accurate measurement method. However, one can also use a calibrated meter to analyze the accuracy of using pH paper or indicator dye (colorimetric) tests.
How accurate are soil pH strips?
pH strips are likely not quite as accurate as a meter.
If you seem to be tracking a trend, such as if the true answer is 5.3 or 5.1, the test is still giving you information you can compare to the last test.