Providing a tree with the ideal soil is the most important thing to do before planting one and when bringing one back to life. By getting the soil to the right pH level, your trees will experience the full benefits of fertilizers and the nutrients available in the soil.
Most trees grow best with a neutral soil pH between 6.0 and 7.0. Some trees like pine and magnolia prefer more acidic soils, while others like bay laurels and blackthorns grow best in more alkaline soils. Check your tree’s ideal pH level before testing and amending the soil to fit its needs.
Read on to learn why pH matters when getting your trees to grow to their full potential, which trees prefer which levels, and how to get your soil back to the right level of acidity. Then you can fully prepare to encourage the growth of your trees and other plants on your property!
Why Do pH Levels Matter?
A soil’s pH level matters because it is one of the major factors that determine how many minerals and nutrients get absorbed by the plant. Messed up pH levels can cause serious damage to the tree and even kill it if left in this state for too long.
Besides controlling how available nutrients are to your tree, pH levels also affect the bacteria in the soil. Soil bacteria in particular releases nitrogen when it eats fertilizer or other organic material, so a pH level outside the range of 5.5 and 7.0 will not get the bacteria moving enough to make the vital nitrogen.
Finally, if the pH level is below 5.0, the soil’s nutrients phase out much quicker, which causes a plant’s health to go south faster as well.
To put it in simpler terms, it is very important to maintain the pH of your yard to keep your trees growing in the best conditions possible.
Which Trees Like Which pH Levels?
There is no specific pH level range that applies to all trees because each species of tree has its own needs for healthy growth. We’ll look at the most common trees in the United States next and the different pH level ranges they thrive in.
Remember to always research your tree’s ideal pH levels before deciding if and how to upgrade the soil.
Trees That Prefer Acidic Soil
If you live somewhere in the Pacific Northwestern, Southeastern, or Eastern part of the country, the soil is generally more acidic. The rainier the environment, the more acidic the soil.
If you live in one of these places, choosing a tree that likes acidic soil makes it easier to maintain the soil health, but you can adjust the pH level on your own if you live elsewhere. I’ll explain how to do so later on.
Luckily, a lot of these types of trees can tolerate higher pH levels (up to around 7.3), but the best growth comes in lower ranges, like 4.5-6.0.
Red oak, maple, dogwood, beech, magnolia, pine, and holly trees are just a few of the species in the U.S. that do well in acidic soils.
Trees That Prefer Alkaline Soil
As opposed to acidic soil, you will find more alkaline soil in places with really dense forests or are super dry, like the Western part of the United States. It is commonly called “sweet soil” by gardeners because it is the opposite of acidic soil nicknamed “sour soil”.
Alkaline soil is often pretty low-quality in terms of structure and high levels of it will stunt plant growth. Clay is one type of alkaline soil that is known for getting waterlogged and cutting off oxygen to the plant.
Some of the types of trees that do well in alkaline soil are Freeman maples, green ash, bay laurels, Rocky Mountain junipers, boxwoods, and willows. Bay laurels and ash in particular can thrive in a pH up to 9.0, while the others can grow well in pH levels up to 8.0.
Most Trees Prefer Neutral Soil
Most trees like neutral soil, not too high or low on the pH scale and around 6.0 to 7.0. Even better, many trees also tolerate a fairly wide range of pH levels.
Cherry, basswood, crabapple, and Douglas fir are some of the tree species that like this neutral soil type.
By checking out pH requirements, you will find most trees can handle slightly acidic soil, but less so with alkaline soils. Now let’s find out how to test the soil’s pH so you can be sure your tree is in its best possible underground environment.
How To Test Your Soil
Whether or not you have planted the tree already, testing the soil’s pH level will help you figure out the best way to encourage growth and allow you to improve the soil. Make sure you know the ideal pH level for your tree before testing, so you know what to do when you find out the results.
Planting a new tree without testing the soil is like sailing out to sea without knowing which harbor you came from. You need to find out the pH level so you can know if and when to use fertilizer. This allows you to boost the growth of the tree through the soil as much as you can without overdoing it.
A lot of gardeners use rapid tests to figure out the pH level of their soil. The Luster Leaf 1601 Rapitest Test Kit for Soil pH is a top-rated test that provides quick results. It tells you about the nitrogen, phosphorus, and potash levels of the soil too. All you have to do is take a soil sample, mix it with water, add in a powder, shake, and voila! Your results come in minutes.
North Carolina University recommends the following tips for taking a soil sample for the most accurate results:
- Use chrome-plated or stainless-steel tools to take out a soil sample because other metals like brass can contaminate the sample and give you the wrong results
- Clear away any debris from the top of the soil like leaf piles and avoid spots with animal waste or standing water
- Dig 6 to 10″ down into the soil and take a sample
- Take 6 to 8 other samples in the nearby area and combine them all
- Remove any large objects from the samples like twigs or pebbles
How To Change Your Soil’s pH Level
So, you have tested your soil and gotten your results—now what? If the pH level is within the range your tree likes, then you are all good! Keep doing what you’re doing.
If the soil is outside of the tree’s ideal pH range, the tree will not grow as fast as it could be. Soils that are too acidic can hamper root growth and soils that are too alkaline cause thinned canopies and slower growth overall.
In a nutshell, soils outside of the ideal pH range for your tree will not allow enough nutrients to be absorbed and will cause multiple deficiencies and problems.
To fix acidic soil, add lime to it, which you can do any time of year. You can use something like Down to Earth Organic Prilled Dolomite Lime for this job. You can apply this product easily by sprinkling it around the base of a tree out to the drip line. Use ½-1 pound of product per 1’ of trunk diameter and water the area generously once you’ve finished.
To fix soil that is too alkaline, Iowa State University recommends using products like elemental sulfur and acidifying nitrogen to make the soil more acidic. Products like Mr. Fulvic Organic Fulvic Acid and Hydroponic Nutrient Enhancer work well to lower pH and make a better growing environment for your trees.
You can apply this particular soil acidifier by adding 5mL of the product per gallon of water. A lot of users have reported improved soil and explosive growth with Mr. Fulvic.
If you are using any other products, check the label for instructions on using it so you do not overdo it with the chemicals.
OK, so you have revived the soil and done the right things to bring the pH level back into the healthy range. Your tree can now thrive!
Now, your next steps are to wait and take care of your trees as usual. You will enjoy the results in the coming months and seasons as the trees grow to their fullest potential from the increase in nutrients and quality of the soil.
Good luck in your endeavors, and remember, you can always call a professional arborist to help you through every step of testing and maintaining soil health. They can take care of everything and encourage your trees’ ultimate growth!
Bradley, Lucy, and Deanna Osmond. “A Gardener’s Guide to Soil Testing.” NC State Extension, NC State University, 20 August 2019.
Chang, Yao-Tsung, et al. “Chemical stabilization of cadmium in acidic soil using alkaline agronomic and industrial by-products.” Journal of Environmental Science and Health, Part A, 1748-1756, 2013.
Everhart, Eldon. “How To Change Your Soil’s PH.” Horticulture and Home Pest News, Iowa State University, 6 April 1994.
Nathan, Manjula. “Fertilizing Acid Loving Landscape Plants.” Integrated Pest Management, University of Missouri, 1 May 2010.
Williston, H.L., and R. LaFayette. “Species suitability and pH of soils in southern forests”. USDA Forest Service. Southeastern Area, State and Private Forestry. Forest Management Bulletin, 1978.