Should We Be Garden Soil Testing?
You’re darn right we should! And, I am going to tell you how to get it done! In this post you will learn about preparing soil for a vegetable garden and the importance of home garden soil testing. But, before we delve into the nitty gritty, you first have to understand the medium you will be using…DIRT !!!
Dirt…what is it…and what’s it good for?
Dirt, or soil, is made up of sand, silt, and clay. The amount of each determines texture. The dirt will have soft areas of small, loose, crumbly stuff as well as harder dirt balls. My BENGAY-covered back is evidence that there is also the more-than-occasional rock to remove. Add in some space for critters, water, and air to move around and, make it any color from deep maroon to brown to black.
The dirt I shoveled as a young-un was as black as you can get. It was nutrient rich and the pH would normally stay in the ideal growing zone with just a touch of limestone (to raise the pH a bit) and fertilizer (normally 10-10-10). It wasn’t rocket science to keep our soil healthy and producing great vegetables.
Rich dirt in The Days of Old…
Having rich dirt was a blessing because, even though we did an occasional pH test with litmus paper, it was next to impossible to get soil testing done for nutrients…at least where we were living.
But, these days, in many parts of the good old U.S.A., the soil seems to be somewhat over stressed and worn out…exposed to a host of man-made contaminations…chemical…biological…too much clay (normally the culprit for insufficient water drainage…lack of crop rotation (a discussion for a future post)…and the list goes on.
There is good news…with all the soil test kits on the market and the easy availability of having soil testing done through county agricultural extension services, it’s a no-brainer.
Do a Soil Test.
Take soil samples from about a half-dozen random areas in your garden (more if you have a larger garden). If you’re like me, you’ll end up with more than a bucketful.
Clear away the surface dirt and, with a shovel or trowel, take a dirt sample at least 4 inches below the surface.
Dry it out. Stir it up to blend it all together. Take out the rocks, twigs, and weeds…and, pour it through a sieve so you will have fine, dry dirt with no lumps or vegetation. Take about a quart of dirt in a plastic baggie to your county cooperative extension office.
At the extension office, they will normally transfer the dirt they need for the test into a special paper bag labeled with your contact information and send it off to a local university for lab testing. The cost for the soil test is nominal…usually less than $10, which is about half the price of the premium soil test kits and you will get detailed results…with recommendations on what type fertilizer and/or limestone you need to make your dirt healthy.
Here are results from soil testing my home vegetable garden.
The nutrients listed are needed at the levels recommended on the graphs to help insure a successful year of vegetables in my garden.
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pH Ranges for a Few Vegetables and Fruits:
Vegetables
| Vegetable | pH Range | Vegetable | pH Range | Vegetable | pH Range |
| Asparagus | 6.0 – 8.0 | Corn | 5.5 – 7.5 | Potatoes | 4.8 – 6.5 |
| Beans | 6.0 – 7.0 | Cucumbers | 5.5 – 7.0 | Sweet Potatoes | 5.2 – 6.0 |
| Beets | 6.5 – 8.0 | Eggplant | 5.5 – 6.5 | Radishes | 6.0 – 7.0 |
| Broccoli | 6.0 – 7.0 | Lettuce | 6.0 – 7.0 | Rhubarb | 5.5 – 7.0 |
| Cabbage | 6.0 – 7.5 | Onions | 6.0 – 7.0 | Spinach | 6.0 – 7.5 |
| Cantaloupe | 6.0 – 7.5 | Peas | 6.0 – 7.5 | Squash | 6.0 – 7.0 |
| Carrots | 5.5 – 7.0 | Peppers | 5.5 – 7.0 | Tomatoes | 5.5 – 7.5 |
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Fruits
| Fruit | pH Range | Fruit | pH Range | Fruit | pH Range |
| Apple | 5.5 – 6.5 | Pear, common | 6.5 – 7.5 | Raspberry, red | 6.0 – 7.5 |
| Blueberry, high bush | 4.5 – 5.5 | Plum, American | 6.5 – 8.5 | Strawberry | 5.5 – 6.5 |
| Cherry, sweet | 6.5 – 8.0 | Raspberry, black | 5.5 – 7.0 | Grapes | 5.5 – 7.0 |
As shown on the Soil Test, the Phosphorus (P), Calcium (Ca), Magnesium (Mg), and Zinc (Zn) levels look pretty good but, I need a bit more Potassium (K). You can see that my pH level is low (5.8). The overall recommendation for a home vegetable garden is a pH between 6.0 and 6.5…a good range in which most of your vegetables will thrive.
“Neutral pH” is 7.0. A garden with a pH lower than 7.0 is acidic and plants may not be able to absorb vital nutrients like calcium, magnesium and phosphorus. A pH higher than 7.0 is alkaline and plants may have a problem soaking up zinc and copper, among other things.
Adding limestone makes the dirt more alkaline.
Adding sphagnum peat, for small gardens, or acidifying fertilizer, for larger gardens, makes the dirt more acidic. If you have container plants, mix 2 tablespoons of vinegar to a gallon of water and water the plants several times over a week to increase the acidity.
At the risk of getting too technical, pH is the scientific abbreviation for “potential of Hydrogen” or, the measure of acidity or alkalinity of a solution or material.
The soil testing done recommended spreading 20 pounds of 16-4-8 fertilizer for every 1,000 square feet of garden space. If your garden if 500 square feet, you would use 10 pounds. If your garden is 2,000 square feet, use 40 pounds.
The numbers on the Soil Test, 16-4-8, refer to the amount of Nitrogen (N), Phosphorus (P), and Potassium (K) in the fertilizer. It calls for a fertilizer containing 16% Nitrogen, 4% Phosphorous, and 8% Potassium.
Nitrogen is crucial as a key part of chlorophyll, needed for plant photosynthesis.
Do the soil testing. Enjoy the harvest. You will never regret it!
Can you see how important it is to know what your garden soil is composed of? Do you soil test your garden plot? If so, you use a purchased kit…or, do you get an itemized soil test from your county agricultural cooperative? Comment below or email me: jim@perfect-vegetable-garden.com.
Now…let’s get…Down & Dirty !!!
Even though I have gardened I casually paid attention to PH and was great to read your article.
It was great that you had the chart in the article which helped to understand the importance looking at the vegetables that wold be effected one way or the other.
I get to save some money as well by going down to the extension. Thanks for writing this.
Thanks, Robert for your positive response. I’ve enjoyed gardening for quite a long time and I really like to see other people get excited about it!
Take care.
Jim
Hello and thanks for sharing, I am glad to see that we are in the seem line of work. I myself have a website that talks about landscape and gardening. Soil is so important because without it we will not be able to enjoy all of those beautiful foods that grace our tables. But what is also interesting is that every thing for the most part comes from soil. One of the main key to gardening successful first of all is knowing your soil type and plant requirements and then moving on from there. Thanks for sharing this awesome post.
Hi Norman,
Thanks, for visiting my website! You hit the nail on the head…everything comes from the soil…and, eventually goes back to the soil. And, every soil has its unique positives and negatives that have to be considered. I bet that growing in Bermuda offers a special set of issues to deal with to successfully grow beautiful, healthy plants.
As they say in Georgia…y’all come back now…hear? Always something new and entertaining, I promise!
Take care,
Jim
Excellent information here. I grew up on a farm in Illinois and my mom and grandma always had perfect gardens with perfect results. My dad would always fertilize the gardens and make sure the soil was ideal for growing just like in the fields. When I moved to Missouri and tried growing my own garden, I had horrible results. The soil was just not like it was back in IL. Nutrients were lacking and I did as you said above and had my soil tested. Lets just say I was better off bringing in nutrient rich dirt and starting from scratch, which I did. It worked great the first year, but it requires yearly upkeep to maintain pH and nutrient levels, but worth every penny! Thanks for you information here!
Yep. That soil test is the key. From one farm boy to another…I guess our dads may have known more about it that we thought they did. Thanks, for stopping by my website. Come back anytime as I add more juicy tidbits.
I’ve always wanted my own garden, Jim, but really haven’t been around to doing it. Well..actually, I don’t think I have the room to be totally honest. However, since I have no idea how to create a fully-functioning garden, this article has definitely helped me out a lot. The table and pH levels will definitely help me out when I get around to creating one.
Thanks a bunch!
-Brandon
Hi Brandon,
Thanks, for visiting my website. I’m glad the soil testing information helped you. As far as “no room”, here’s an excerpt from my “About Me” page:
In the smallest apartment I ever had (a lot less than 500 square feet and no outdoor space), my closet was full of flower pots and grow lights that produced several types of vegetables. Needless to say, I found some unique ways to store my clothes since there was absolutely no room in my “garden closet.”
Even though it may be a space challenge, at times, you can always grow something and still enjoy the “fruits of your labor.”
Take care and come back often.
Jim
Hi Jim,
I really enjoyed your article and appreciate your increasing my awareness of a gardening issue I’ve really never thought about. For the most part, I do container gardening and I purchase potting soil. Still, I assume that all potting soil is not equally effective for all applications and it may deteriorate over time. My results are not always what I had hoped for so the quality of my soil may be part of the problem. I will take your advice and do some testing. Thanks for the info!
Hi Linda,
Many people who have container gardens think that planting with potting soil means they never have to add any nutrients after that. The truth is…plants feed…just like people. As they feed, nutrients leave the soil and are absorbed into the plants. When the nutrients are gone from the soil, the plants will not be able to feed anymore and, they will starve…just like people.
A soil test will definitely let you know if your soil is deprived of any essential nutrients or, if your pH level is not adequate. pH level is important, too. If the pH is not in a range that your plants are comfortable in, they can not feed…even if the soil contains the right amount of nutrients.
The right amount of nutrients and the correct pH level go hand-in-hand in keeping your plants healthy and happy.
Glad you stopped by. Take care…and come back soon!
Jim