I’m sharing the signs of acidic soil (low soil pH) and how to make it more alkaline. Your garden soil may look and feel like fertile soil but that doesn’t necessarily mean that you’ll have the best or healthiest production when you try growing fruits or vegetables. If your soil is too acidic (low pH level) or too alkaline (high pH level), plants can’t absorb the essential nutrients and will suffer.
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Most home gardeners will already know most of what’s in this post. However, if you’re considering growing some of your own food for the first time or if you want a healthy lawn, you might find this post helpful.
When it comes to garden soil, it’s important to know what’s in your soil and what it may lack.
You need a soil test to know your soil’s pH level and how much, if any, lime or sulfur is needed to change the pH to bring it into the optimal range for what you want to grow.
A lime application will sweeten your soil (raise the pH) and sulfur fertilizers will make your soil more acidic (lower the pH).
Get a Soil Analysis Before You Start Planting Your Garden
I recommend that gardeners get a chemical soil analysis of the area they want to turn into a garden BEFORE they start digging.
Collect soil samples for your soil analysis.
It’s important to take a composite sample of the area you want to plant in.
A composite sample is a collection of 6 to 10 uniform slices (or cores) of soil taken from random spots in the area you want to turn into your garden. For accurate soil testing, mix together all the samples from the designated area. (I generally use a bucket.) Then put about two cups of the mixture into a waterproof bag and into a soil sample box along with a note on what you intend to grow.
You can call your county extension office for information and to get a soil test kit, but a good local garden center may also have what you need to send off your sample.
A routine soil analysis in my state costs around $10. Once the laboratory receives the sample, it takes them about a week to send the results back via email or regular mail.
The soil analysis measures the pH level of your soil and the amount of nutrients in the soil sample.
The chemical soil analysis measures the soil type, soil pH level, nitrogen, phosphorus, potassium, and other nutrients and minerals. (Specific analysis will depend on your state.)
Nitrogen promotes healthy plant growth (stem and leaf growth). If lettuce or other leafy crops turn out poorly even when they get enough sun and water, your soil is probably deficient in nitrogen.
Phosphorus helps plants set their roots quickly and vigorously which in turn promotes flower and fruit development. If you have a lot of leafy vine growth on your tomato plants but not a lot of tomatoes, your soil is probably deficient in phosphorus.
Potassium helps fruit development and keeps roots healthy and disease-resistant. If your potatoes and carrots look pitiful, your soil is probably deficient in potassium.
However, nutrient availability doesn’t matter if your soil pH isn’t where it needs to be for what you want to grow. You can waste hundreds of dollars adding fertilizers and amendments but end up with poor crop yields if the soil is out of the preferred pH range. Your plants will show signs of nutrient deficiencies when the pH of the soil is incorrect.
Soil pH Measures the Soil’s Acidity
If your soil is too acidic (“sour” or “low pH”) or too alkaline (“sweet”, “basic”, or “high pH”), your garden won’t grow right.
I wrote a post on if clay soil is acidic (low pH) or not. I encourage you to read it if you think you know the answer!
The pH (potential hydrogen) scale measures the activity of the hydrogen ion in a substance. In lay terms, if the concentration of hydrogen ions is high, the substance is acidic and the pH is less than 7. If the concentration of hydrogen ions is low, the substance is basic or alkaline and the pH is greater than 7.
The pH scale goes from 0 (acidic) to 14 (alkaline) and each number is multiplied by a factor of 10. For example, pH 6 is ten times more acidic than pH 7 and pH 6 is 100 times more acidic than pH 8.
The chart below will help you determine where your garden soil falls on the pH scale. Your soil analysis will list your soil’s pH along with recommendations to change the level to where you need it to be.
- pH > 7.3 = alkaline conditions
- pH 6.6–7.3 = neutral point
- pH 5.8–6.5 = slightly acid; ideal for most crops
- pH 5.0–5.7 = very acid; ideal for acid-loving plants
- pH < 5.0 = strongly acid; lime recommended for all crops except blueberries
Signs of Acidic Soil (Low pH)
Certain types of weeds, plants, and trees prefer acidic soil and will thrive when soil has a low pH level. Observing what’s growing in your area will clue you in on what the pH range is.
Most evergreen trees including magnolias, cedars, and pine trees prefer acidic soil. Some deciduous trees that also like sour soil are oaks, willows, dogwoods, and beech trees.
Shrubs like blueberries, blackberries, holly, azaleas, rhododendrons, hydrangeas, and camellias also prefer acidic soil.
I don’t like the term “weeds” because of the negative connotation for a usually useful plant. However, plants that fall into this category and that thrive in acidic soil are plantain, dandelions, nettles, mullein, and broom sage (sometimes called broomsedge and broomstraw).
The problem with soil that’s too acidic or alkaline is that it ties up the nutrients so that plant roots can’t absorb them.
Most fruit and vegetable plants prefer a slightly acidic soil with a pH of 5.8–6.5.
When we moved to our farm, all the pastures were covered in broom sage and cedar and pine tree saplings were popping up everywhere.
Since the pastures were important for grazing our cows, we needed to get the soil pH fixed so that regular grass would grow.
How to Make Soil More Alkaline
You can add a soil amendment to increase the alkalinity of the soil and it doesn’t have to cost that much.
The soil analysis you receive from your extension office will probably include some recommendations for adjusting the pH but I wanted to include a few for informational purposes.
The best way to sweeten your soil is to add lime. Most farms will add limestone to improve soil alkalinity. That’s land lime and not the lime that masons use to make cement.
Ground limestone mixed into the soil at a rate of 10 pounds per 1,000 square feet will raise the pH one full unit, so 5.5 to 6.5. Lime treatment takes time to neutralize soil’s acidity, though, so count on it taking between 6 months to a year or longer. The best time to apply lime is in the fall so the soil can absorb it over winter.
Another option to sweeten your soil is to add animal manures and other organic matter.
In my area, sometimes we get the best results when chicken litter is spread over fields to decrease the soil acidity and therefore suppress acid-loving weeds and promote healthy green grass for grazing. But other animal manures will work just as well.
If you overwinter any livestock and have a huge compost heap by your barn in the spring, try spreading it onto your fields where you see a prevalence of acid-loving weeds.
The more you sweeten your soil pH, the less you’ll see the acid-loving weeds and tree saplings pop up. The soil won’t be as palatable to the seeds!
Soil pH Levels Vary Across the United States
I came across a wonderful site by Earth Science that lists the general soil pH levels across the United States.
Generally, the Eastern, Southeastern, and Pacific Northwest have acidic soils. Rain washes away alkaline elements from sandy soils. The exceptions are in river basin areas that have more alkaline soil.
The Western half of the United States is more alkaline because there is less rainfall and the underlying rocks are alkaline shale or limestone and not acidic granite.
Soil in the Midwest and Great Lakes are close to neutral due to generations of intensive farming.
Conclusion: Signs of Acidic Soil (Low pH) and How to Make it Alkaline
If you’re planning on putting in a garden where you see a lot of broom sage and pine tree saplings, your soil is probably too acidic for most plants.
To remedy the situation, take a soil sample and send it off to your local extension office to get a soil analysis. Depending on the pH of your soil, add lime and animal manures in sufficient quantity to bring up your soil’s pH level to where it needs to be for what you intend to grow.
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Other Related Posts
Use Vinegar to Acidify Soil (Lower pH) for Blueberries
Gardening: Is Clay Soil Acidic (Low pH)?
How Much Worm Castings Should You Add to Soil?
Laboratory Soil Testing and Resources for Gardeners
Our soil is so acidic, but we get wild blueberries and huckleberries everywhere! I would love to grow a few things-I’m thinking we’ll have to do raised beds.
I’d love to have access to wild blueberries! We have really acidic soil too and that allows us to wild harvest all the blackberries we want, which are considered invasive weeds where I live! There’s always a silver lining. =) Raised beds are a great solution to improve soil structure and pH.
I never realized how much you need to know in order to live on a homestead. This was very informative, thank you!
I think you can live on a homestead no matter what you know and most things we just figure out as we encounter issues. The good news is that the homesteading and farming breed of do-it-yourselfers thrive on sharing their knowledge and helping others reach the same goals we have set for ourselves. I’m always learning something new from the old-timers and I love hearing from them. I’m glad you found this post helpful!
This is such important information for anyone trying to grow something in their garden. I love that you made this post so easy to read and understand!
Great information! Thank you so much!
This is such great info! We just moved to a new state and want to start gardening, so now I know to check the soil levels first. Thanks for sharing!
Great information. Think I need to get my garden soil tested.