How and When to Test Your Soil PH

If you’ve read any number of previous Kellogg Garden articles, you’ll know that we are soil fanatics. The health of any individual plant or garden as a whole is only as good as the soil it’s planted in, so for us, it all starts with good soil. “That’s great,” you might say, “but how do I know if my soil is healthy?” Well, lots of different ways, but one tried-and-true method is the soil test.

Before we get into how to test your soil, let’s talk about the what and the when. A soil test tells you what your soil pH is (alkaline or acidic) and from there, pinpoints any nutritional deficiencies. Once you’re armed with this information, you can amend your soil, giving it exactly what it needs to allow your plants to grow happy and healthy. You can perform a soil test any time of the year, but fall is preferable — simply make it a part of your annual fall garden routine. Similarly, go ahead and do a soil test if you consistently experience unhealthy plants in an area of your garden for no discernible reason.

Hands holding soil with a plant

So, now you’re ready to test, but how do you do it? You’ve probably heard of a wide range of recommendations, starting with your next-door-neighbor to your newspaper’s garden column, and all the information gets confusing, right? So here’s a rundown of ways to test and amend your soil.

Send a soil sample to your county extension office. This will arguably give you the most reliable results. Your extension office will give you instructions on collecting a soil sample, and will give you a soil analysis for free or for a very low fee. There are private testing laboratories that perform plant tissue and soil testing, though, and although they may cost more, you might be able to get a more detailed analysis like levels of micronutrients calcium, magnesium, copper, zinc, iron and manganese.

Buy a soil-testing kit from your garden center. Although I’ve used these many times with fairly accurate results, the results can vary widely from one kit to another. And this option may not be as thorough with detail as a laboratory test, but it’ll give you your basic pH and nutrient results in real time for a low cost. This is a great way to go if you simply want a good baseline soil test and aren’t experiencing significant soil issues, but I’d get a recommendation from your garden center on which kits are the most reliable.

Senior farmer looking at the soil on the corn farm.

Do a DIY soil test. If you like DIY projects but aren’t too concerned with depth of detail, try this PH test. Collect 1 cup of soil and separate it into two containers. In one container, add ½ cup of vinegar — if it starts fizzing, then you have alkaline soil, which typically has a pH between 7 and 8. Now, if it doesn’t fizz, turn your attention to the other container. Slowly add distilled water to the soil in that container until it’s a bit muddy, then add ½ cup of baking soda. Does it fizz? You have acidic soil, with a pH between 5 and 6. If your soil didn’t fizz either time, congratulations! You’ve got soil with a neutral pH of 7, which is what most plants prefer. To be clear, I’ve heard varied opinions about this type of home testing from people whose experience I respect, so while it could give you an idea of what your soil is, it’s probably not definitive. I could imagine having a laboratory test performed and then comparing it, for fun, with the results of this DIY test, though — it could be your own version of Myth Busters: The Garden Edition!

Amend Your Soil. When determining whether your soil should be acidic, neutral, or alkaline, you need to think about what you intend to plant in that soil. Most plants prefer a neutral or slightly acidic soil environment, but some plants thrive in an alkaline environment. If the results of your soil test show that your soil is acidic, you can raise the pH by mixing in ground limestone, wood ashes, or oyster shell. On the other hand, if your soil is more alkaline, you can lower the pH by mixing in organic materials such as fir bark fines and peat moss. Kellogg Garden Organics Shade Mix is a great mix to lower your soil’s pH, as it has a balanced pH between 4.5-5.5 in which acid loving plants thrive. Shade Mix can be mixed into your native soil or used directly out of the bag as a potting mix.

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hand holding brown soil with a green plant


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    • Hi Frank, one place to start is your nearest extension office, you can contact them to ask about their rates. They’re also a great resource on local soil and growing conditions. The University of California Cooperative Extention has a map to help you find the nearest office, you can see it here: . However, you can also go to your local garden centers and plant nurseries or order a soil testing kit online for as low as $10. Ask or check reviews for testing accuracies, some of the kits are more expensive but they are more accurate and can be used more than once. We hope this helps, let us know if you have any other questions.

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