Last Updated on October 31, 2021 by Phil
How to test soil in your home garden. Garden soil testing is an essential step when starting a garden. And, it is something you want to do on a regular basis to make sure that your soil is in its best condition to for plant growth.
After all, if you’re going to spend months one end planting and caring for your flowers and vegetables, isn’t it worth it to spend a day to make sure the environment you’ll be planting them in is the right one.
The best part about garden soil testing is that there are inexpensive, easy to use home soil test kits readily available.
This lets you do everything at the comfort of your own home.
To help you get started, I’ll take you through the entire process from start to finish below.
Why Soil Testing is Important?
Like people plants need nutrition. And, for plants grown in the ground, soil is what provides the nutrients for them to grow optimally, be healthy and produce lots of flowers and vegetables.
Unfortunately, there is not way to tell how much nutrients or how healthy your garden’s soil is just by looking at it.
Soil testing is a quick and easy way to know that kind of soil you have, its composition and the amount of nutrients it contains.
Additionally, just because you have nutrient rich soil does not mean that plants will be able to absorb all those minerals. That’s because of soil pH.
Soil pH measures the level of acidity or alkalinity of soils. This figure ranges from 1 to 14 with 7.0 being considered neutral. Anything below a pH of 7.0 is acidic and any number above 7.0 is considered alkaline.
More importantly, soil pH affects how much nutrients the plants are able to absorb in the soil. In simple terms, you want to match your soil’s pH with your plants’ preferred pH levels.
When you do so, you’re able to maximize the available of essential nutrients your plants can get from the soil.
It is worth noting that most plants including crops prefer soil with pH between 6.0 and 7.5. That level runs from slightly acidic to neutral pH.
However, some plants do better in acidic soil with pH running from 4.5 to 5.5. Some examples of these include blueberries, gardenias and azaleas.
Similarly, few plants do better in alkaline soil. Lilacs, crocus and forsythia are a few examples of this.
By testing your soil, you’re able to determine what pH your soil has and if you need to do anything to fix the issue to help your plants grow optimally.
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When Should You Test Your Soil?
If you’re starting a new garden, the best time to test your soil is early spring. This gives you enough time to get the results (it takes longer if you send it to the lab) and then make the necessary amendments to improve your soil before you start planting.
The time also allows the soil to adjust to your changes before you kick off your planting activities.
On the other hand, if you’ve already been panting, the best time to test your soil is after each gardening season.
This way, your results are based on somewhat “spent” soil where the plants have taken what they needed from the soil and possible changes to the soil have happened during the previous growing season.
Here, you have a couple of options.
You can do it in the fall or early spring. Some people prefer early spring because it gives you just enough time to make the changes. And the soil to adapt before you plant again.
However, if anything happens, something gets delayed along the way or life somehow gets in the way, you won’t have a lot of time to get everything done. Or, you may end up hurrying.
As such, many growers prefer testing their soil in the fall. The bigger your plot is, the more important or commercial your crops are, the earlier you want to get the soil tested.
This gives you more time to get the results (this isn’t a problem for DIY home testing kits), buy the fertilizer, lime, compost or organic matter, and then make the necessary amendments.
That said, both fall and early spring work well.
Additionally, if where you live does not experience any snow, you can likewise test in the winter since the weather is warm.
Whichever time you choose to test your soil, it is very important to be consistent with it. Additionally, follow the proper procedures based on the soil test kit you’re using. If possible, use the same one each time (provided that it is reliable) and be consistent with he sampling process as well.
Last but not least, don’t think that just before fall and spring are the recommended time periods to test your soil that you can’t do it any time.
In fact, you can take test samples any time you want and have it tested. So, if you feel something isn’t going right or you have suspicions about the soil at any point in time, just have it tested.
Having a home soil test kit makes this very inexpensive, easy and convenient.
How to Test Soil
The following steps on how to test soil are done with a home soil test kit. This is very different than if you were to send soil samples to a lab. If that’s the case, the lab will give you proper instructions on how to collect soil samples.
From there, you’ll mail it to them and wait for further instructions.
While that’s more accurate, it also takes longer. Plus, it costs quite a bit more.
On the other hand, home soil test kits are inexpensive, fairly fast and very easy to use. Best of all, you can do it yourself at home.
And, I’ll take you through the entire process below.
How to Collect Soil Samples for Testing
Before you begin using the soil test kit, you’ll need to collect soil samples. I recommend reading the instructions that come with your soil test kit since each manufacturer will have different instructions as to how to take a soil sample and how much to get.
In concept, they’re all similar. But, there are details you don’t want to skip based on the kind of soil test kit you have on hand.
Taking the soil sample is easy. But there are a few things you want to consider before starting.
- Make sure to clean all the tools – this includes the trowel and the bowl. You don’t want any minerals, chemicals or previous dirt or anything else to skew the results. Also, don’t use your hands to collect the soil.
- Pick out the spot in your garden – this depends on whether you’re planning to test your entire garden or just a section of soil.
- Check how much soil you need to take – this will also affect the size of your bowl since you’ll add water later to it. In my case, the soil test kit requires one cup of soil plus 5 cups of water for the N-P-K tests. Then about a tablespoon of soil and a little bit more water for the soil pH test. So, the bowl, should be able to accommodate this amount with a little extra space.
Once you know all these things, it is time to scoop the soil and place it into the container.
How To Test Your Soil At Home Step-By-Step
Below I’ll go through the step by step process of testing your soil for N-P-K using a soil test kit. And, after that, do a soil pH test using the pH tested that’s included in that same home soil test kit.
Since the two processes are similar but not exactly the same, I’ll go through all the details below.
How to Test Soil Nutrients (N-P-K)
In your soil test kit, testing for nitrogen (N), phosphorus (P) and potassium (K) takes the most time (12 to 24 hours or so). As such, you’ll want to be prepared for that.
Note that different kits will come with different kinds of tests of N, P and K. As such, the containers may be different and the process may vary a bit as well.
Although, the overcall concept is the same.
So, always makes sure to read and follow the instructions included in your soil test kit.
How to Test for Soil Nitrogen, Phosphorus, Potash (N-P-K) Step by Step
Before you begin, it is a good idea to have gotten the soil sample (from above). You’ll be using the soil sample for the test.
Honestly, the 3 tests are very similar in that the process of doing each it the same. So, once you get the hang of one, just repeat the process for the rest.
Here’s how to do it.
Step 1: Add Water to Soil Sample
You’ll start with clean bowl and add soil sample to it. I like to use a glass bowl like the pyrex ones or something with a snap on lid. You also want to get a tall bowl since there’s a higher ratio of water to soil.
Use distilled water since it does not contain any minerals. Tap water often has chemicals added to it. So, you want to avoid that since it will affect your results.
Follow the amount of water to soil ratio that your test recommends. In my case, it is 5 cups of water to 1 cup of soil. So, the bowl has to be high enough to take 5 cups of water plus the extra from the soil.
Step 2: Mix the Water and Soil
If you used a pyrex-type of bowl, you can stir the soil and water to mix it. If your glass container comes with a snap on lid, you can tightly close the lid and shake the mix the contents.
You’ll need to mix vigorously to mix everything since the crumbs of soil will take a bit to mix with water.
Step 3: Let it Settle
This is the longest part of the test. Be ready to wait at least overnight or up to 24 hours.
The goal is to let the soil settle to the bottom and the water become fairly clear. This takes a really long time so I suggest just leaving it and go about your regular daily routine in the meantime.
Note that the type of soil you have will also affect how long it takes. Sandy soil is faster so about overnight will do. But, clay soil will take much longer.
Step 4: Fill the Containers with the Soil Water
Your test kit will come with a dropper. You can use that to fill both chambers (the left and right sides) of all 3 containers up to the fill line at the back of the container.
Don’t underfill or overfill the container. Just look for the fill line (which will leave some space on the top).
Step 5: Add the Appropriate Powders
Make sure that you put the corresponding test powder to the appropriate container. The powder is contained in the capsules which are color coded to match with the containers.
Then pull apart the capsules to let the powder drop into the left chamber (none on the right, which is the test case that shows you the original color).
Ideally, you want to do this somewhere that isn’t windy or where there’s an fan that can blow the powder.
Step 6: Shake Each Container
Once you’ve filled the left side chamber of each of the containers, put the lid on. Then, shake to mix everything together. You want the soil to dissolve with the water.
Then leave the 3 containers on a table and allow the soil to settle. It will take a few minutes for the soil to settle to the bottom.
Step 7: Check and Analyze Your Results
Now for the fun part!
Once the soil settles to the bottom of the containers, it is time to check the color of the water against the color labels.
This will tell you if your soil is deficient, sufficient or high in nitrogen, phosphorus and potash.
Here’s a video to show you the process of using a soil test kit for nitrogen, phosphorus and potassium (N-P-K).
How to Test Soil pH Levels
The soil pH test is another very important test to do. It is much easier and shows you the results faster as well.
In concept, soil testing kits will make you do more or less the same thing. But, you always want to read the instructions carefully and follow them according the manufacturer’s specifications.
Like above, you’ll need to take a soil sample to do the test. But, you’ll likely need less soil for the pH tester.
Note that soil pH testing kits can come on its own. So you can buy them individually if you don’t need to do the other tests. But, they also come as a package with the other tests.
However, with the latter always check since some home packages don’t come with soil pH testing.
Finally, it is worth noting that you have other options to testing the soil pH besides a using a kit. You can instead purchase a soil pH meter or a soil pH probe.
These are devices that you stick into the ground and will tell you the pH level of the soil. If you do get one, be sure to do your research and use a high quality product since not all are reliable.
You can likewise double check it against a soil pH test kit a few times to check its accuracy before making it a staple in your gardening toolbox.
Here’s how to test your garden’s soil pH with a soil pH meter.
How to Test Soil pH Step by Step
Here’s a step by step breakdown of how to test your soil’s pH level.
When you get the soil pH testing kit, you’ll get a small container and packet containing capsules. That’s all you’ll need. Also have some distilled water on hand to mix the contents together.
Then follow the steps below..
Step 1: Add Soil Sample into the Container
Once you do, you’ll see the soil sample on the left side and the color pH labels to the right.
Note that the opening is small so you can use a small scooper or make a paper funnel to easily get the soil into the hole.
Step 2: Add the Powder Provided
The small ziplock plastic that comes with the kit will contain green tablets. You’ll be using the content contained in the green tablets to mix with your soil.
Note that you won’t drop the capsule into the container. Instead, you’ll open it and drop the powder into the opening of the container.
When doing so, avoid windy areas since it will blow the powder all over the place which leaves you with less for the test.
Step 3: Add Water
Use distilled water for this. This way, the water does not get in the way of the pH levels. Distilled or ionized water have neutral pH. So, you can use either.
You do not want to use tap water since that is often alkaline in nature. In contrast, rainwater is acidic. So, stick with distilled water.
Step 4: Shake the Container
And yes, I mean shake it like you mean it. You’ll need to do some vigorous shaking to make sure that everything mixes together. I’ve learned that it does not help to shake gently.
Much like mixing juice concentrate or protein powder, you’ll want to shake it well.
That said, you only need to shake it for a few seconds.
Also, make sure to snap the lid on tightly so the contents don’t spill.
Step 5: Wait for the Results
After you shake, you’ll need the soil mix in the entire solution. This will make the water look light brown which is fine.
Then just leave the container on a table and the soil will settle. It will take a few minutes for the soil to slowly drop all the way down to the bottom of the container.
This is fairly fast so you can just walk a way a bit and come right back.
Once the soil is all at the bottom, you’ll notice the water color change. This is your result.
Because you’ll be matching the color of the water with the color of the labels to the right, you’ll need to put the container against some kind of light. This makes it a good idea to do the test during daytime.
The color of the water will tell you the pH level of your soil.
Here’s a video of the entire process.
How to Improve Acidic Soil
If your garden soil is acidic, you’ll need to add garden lime or limestone to amend the soil. This will bring up the soil’s pH levels. How much you need to put will depend on the current pH and your target pH levels.
Lime also contains calcium and magnesium, both of which are important nutrients plants need to stay healthy.
Keep note that reducing soil acidity levels take time. And, because soil is mostly on the acidic side, most growers like to test soil in the fall in order to give the lime time to do its work through the winter.
To give you an idea, most soil in the eastern part of the country are acidic in nature. Similarly, the northwest, and regions of Hawaii and Alaska likewise have acidic soil.
How to Improve Alkaline Soil
On the other hand, if you find that your garden’s soil is alkaline in nature, you’ll want to get hold of sulfur. This is the case for most areas in the Central and Southwest.
Adding sulfur, which also happens to be another important nutrients plants need, reduces the soil’s pH level. More importantly, alkaline soil hinders iron absorption.
Consider Raised Bed Gardening
Finally, depending on how much your soil needs to be amended, you may want to figure out the best approach.
If you have a small garden, then amending the soil is less of a problem. However, if you have a large plot and realized that its pH is way off, you may want to take a different approach.
That is, for certain sections of your garden, you may pick the plants that are ideal for that soil pH.
And, if there are vegetable, plants or flowers that you’d really like to grow that require a different soil pH, it may be a better idea to use garden beds instead of trying to modify your entire yard’s soil pH.
The advantage of garden beds is that you’ll be adding your own soil on top of the ground. Thus, you can use a custom soil mix that’s perfect for different types of plants you wish to grow.