How to Test Garden Soil Using a Home Testing Kit

Testing your own garden soil at home might sound intimidating at first, but it’s actually quick, affordable, and super simple. You don’t need to send samples to a lab or spend a bunch of money to get accurate results.

In this post, I’ll walk you through the entire process step-by-step. Once you know what your soil is lacking, you can add the right amendments to give your garden the best possible start.

Why Testing Your Garden Soil Matters

All plants need nutrient-rich, fertile soil to grow their best, stay healthy, and produce tons of flowers and vegetables for you to enjoy.

But here’s the thing – it’s impossible to tell if your garden soil is healthy just by looking at it. You have to test it to know for sure.

A quick DIY test will show you exactly what your soil has too much of and what it’s missing, so you can add the right amendments to fix it.

When to Test Your Garden Soil

The best time to test your soil is in the fall, at the end of the gardening season. That way, you’ll have plenty of time to add any amendments before spring rolls around.

You can also test it in early spring to see if the soil has improved or if it needs a little extra help before planting.

How Long Does an At-Home Soil Test Take?

The time it takes to get your results depends on the type of test you’re doing. But either way, it’s the prep work that takes the longest. Here’s a breakdown of what you can expect:

• pH test: This one is the quickest, and the total time is about 10 minutes. After collecting your soil sample and preparing the test container, it only takes about one minute to get the results.

• N-P-K tests: These 3 tests are a little longer, and the total time can be up to 24 hours. It takes some time to prepare your sample (especially if you have clay soil), but once it’s ready, the results show up in about 10 minutes.

Everything You Need for a Simple Soil Test

Your soil test kit should come with instructions for use. So make sure you review those first, because they might be slightly different than my steps below.

My kit came with four different color-coded containers for testing each of the main nutrients. Pink for nitrogen (N), blue for phosphorus (P), orange for potassium (aka: potash) (K), and green for pH.

In addition to your kit, you’ll need a few other supplies before you get started:

• DIY soil test kit
• Clean container (I used a kitchen bowl)
• Clean garden trowel or large spoon
• Distilled water
• Measuring cup (1 cup)

How to Take a Soil Sample

The first step for all four of the tests is to take a soil sample. Taking the sample is really easy, but make sure your tools are clean first.

Use a garden trowel or large spoon (don’t use your hands), and also grab a large bowl or other container to put it in.

Remove any mulch or debris from the top of a small area of the soil, then dig down about 3-6 inches to take your sample (the garden bed in the photo below is new, so there isn’t any mulch on top yet).

If you want to do all four tests in the kit, you’ll need a little more than one cup of soil (one cup for the N-P-K tests, and less than one teaspoon for the pH).

Step 1 – Mix your soil sample with water: In a clean bowl, mix one cup of your soil sample with five cups of distilled water.

It’s important to use distilled water rather than tap water to ensure your test results are accurate (tap water contains chemicals and minerals that can skew the results).

Step 2 – Let the soil settle: Stir or shake your soil and water mixture for about a minute, then let it sit until everything settles and the water clears.

Clay soils can take up to 24 hours to fully settle, while sandy soils clear faster. Don’t rush this part – the clearer the water, the more accurate your results. I usually let mine sit overnight.

Step 3 – Fill the test containers: Once everything has settled, make sure you don’t move the soil sample/water mix, or disturb the muck at the bottom. You’ll only be using the water for these tests.

Fill both chambers of the N-P-K testing containers with your sample water up to the line towards the top. Your kit should come with a little dropper to make it super easy.

Don’t fill the containers all the way to the top though, you’ll need a little bit of headspace to shake them up after you add the test powder in step 4.

But make sure water level is above the colored boxes (it’s really hard to see, but there is a very faint dotted line at the top of left chamber to indicate the water level).

Step 4 – Add the test powder: The capsules that come with the kit are color-coded to the respective containers. So grab the one that matches your test container.

I recommend doing this next part in an area where there’s no wind. Also, be careful not to inhale the powder or get any of it in your eyes or mouth.

Pull apart the capsule and pour the powder (not the entire capsule) into the left chamber only. Don’t get any powder into the right side compartment, that water should stay clear for comparison.

2. Testing Soil pH Levels

The pH test works a bit different from the N-P-K ones, and it’s much faster. You’ll need less than a teaspoon of soil.

But make sure to follow the same method to take your sample as I described above (no hands, clean tools, etc.).

Follow the steps below to test your soil using a pH using the DIY kit. (If your kit didn’t come with the green container, you can buy a separate pH test kit or use a pH probe).

Step 1 – Put your soil sample into the test container: Add a small amount of your sample soil to the left side chamber to fill it to the line (it’s really just a tiny bit).

I tried using the dropper thingy for this, but that does not work, so don’t do that. I found it easier to use a small spoon to get the dirt in there.

You don’t have to be too fussy or worry about getting dirt into the right side compartment. And if you accidentally fill it above the line, then you can just pour out the extra. No biggy.

Step 2 – Add the test powder: Grab a green capsule (or whichever one came with your kit) and carefully open it. Then pour the powder into the left chamber, right on top of your soil sample.

Again, I recommend doing this in a spot where there’s no wind. You don’t want the powder blowing away, or getting into your eyes or mouth.

Step 3 – Add distilled water: Fill the rest of the left side compartment with distilled water up to the indicator arrow (this is where you can use the dropper thingy). Leave the right side of the container empty for this test.

It’s best to use distilled water for your pH test, just in case there are chemicals in your tap water that will skew the results.

Step 4 – Shake and wait: Snap the lid tightly on the container, then shake the heck out of it to mix the soil, powder, and water together. Let it sit for about one minute before reading the results.

How to Read Your Soil Test Results

To read your results, hold the test container up to natural light (but not direct sunlight). Then, compare the color of the water on the left side to the color chart on the right.

If your soil is really lacking in one or more of the N-P-K nutrients, you’ll notice that the water on the left will be almost colorless. On the other hand, the darker the color on the left side, the higher the nutrient level in your soil.

You can see from my N-P-K tests (photo below) that my soil is deficient in nitrogen (pink), sufficient in potash (orange), and has a surplus of phosphorus (blue).

Same idea for the pH soil analysis: Simply compare the color of your sample on the left to the chart on the right. The color chart will show you how acidic or alkaline your soil is.

You can see from the results of my pH test (the green one on the right), that my soil is alkaline.

Blog Post Summary

Soil testing is a game-changer for gardeners at any experience level, and a DIY test kit makes it so easy to do it yourself. Once you understand your soil’s N-P-K and pH levels, you’ll have all the info you need to improve it.

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