Why Soil Testing Is the Key to a Healthy Garden: How to Test Your Soil the Right Way

Unlock Your Garden’s Full Potential by Understanding Soil pH, Nutrient Levels, and Organic Matter

You wouldn’t build a house without a solid foundation, and the same goes for your garden. Healthy soil is the foundation of a thriving garden, but you can’t always tell if your soil is up to the task just by looking at it. That’s where soil testing comes in. A soil test reveals critical data about your soil’s pH, nutrient levels, and organic matter, giving you the tools to grow stronger, healthier plants from the ground up

Watch: Step-by-Step Soil Testing Guide for Gardeners

You can buy soil tests at garden centers, hardware stores, and online. But our preferred method is to test our soil at the Colorado State University Spur Soil Testing Facility. If you don’t live in Colorado, check with your county extension office for local programs near you. But, before you purchase a test kit, be sure the test will explain the final results and give suggested fixes, and not just send raw data for you to decipher.

What will you learn about your soil from a test? A good soil test will tell you:

Soil pH levels – This will tell you your soil's acidity and alkalinity levels. Plants thrive in balanced soil, so if it is too acidic, you may need to add lime or wood ash to lower it. If it’s too alkaline, you might want to add sulfur, gypsum (calcium sulfate), or organic matter like compost or peat moss to bring it into balance.

Soil nutrient levels – The test should tell you the levels of macronutrients in your soil, such as magnesium, calcium, phosphorus, and potassium, as well as the micronutrients. Knowing these levels will help you choose the amendments your soil truly needs, rather than guessing and possibly making the problem worse by adding more of something you already have too much of.

Organic matter – Organic matter is vital to soil health. It feeds your soil with nutrients, improves water retention, and promotes microbial activity. If your test shows low levels of organic matter, consider enriching your soil with high-quality compost like our premium worm castings. They boost microbial activity, enhance nutrient absorption, and improve soil structure naturally.

To get the best results from your test, there are some best practices to follow when gathering your soil sample.

First, use a clean trowel or soil probe — no rust or residue. A clean apple corer is a great option.  

Second, figure out the zones in your garden you want to test.  For example, one zone could be in-ground planting, while the second zone might be a raised bed.  Maybe you want to test a zone where weeds are a persistent problem to better understand why?  But keep in mind, labs will charge you for each zone you send in, so don’t go crazy breaking your yard into a thousand different zones.

Third, gather your soil. Most labs want two cups of soil per zone for their testing (check the specific amount of soil your lab needs). To get two cups of soil, break your zone into 4 separate sections and take a half cup of soil from each section.

Step four: combine the soil in a clean bucket, mix well, and let it air-dry for 24 hours on a paper towel.  Please don’t believe the myth that you should cook your soil sample in the oven first.  That just destroys some of the nutrients and will skew the test results. 

Finally, after it has air dried for twenty-four hours, scoop your sample into a labeled bag or container.  Label the sample by area: veggie bed, flower bed, lawn — whatever helps you track where it's from, and mail it off. Note, some labs send containers for the soil sample, while others just ask for a clean plastic bag. Check kit instructions before mailing.

Once you get your results back, please use them! Soil testing might not feel exciting, but it’s the smartest move you can make for a healthy garden. Let us know in the comments what your soil test taught you about your garden!